diff --git a/ppocr/modeling/architectures/rec_model.py b/ppocr/modeling/architectures/rec_model.py
index 26146204..d0441c05 100755
--- a/ppocr/modeling/architectures/rec_model.py
+++ b/ppocr/modeling/architectures/rec_model.py
@@ -25,6 +25,12 @@ from copy import deepcopy
 
 
 class RecModel(object):
+    """
+    Rec model architecture
+    Args:
+        params(object): Params from yaml file and settings from command line
+    """
+
     def __init__(self, params):
         super(RecModel, self).__init__()
         global_params = params['Global']
@@ -64,6 +70,12 @@ class RecModel(object):
             self.num_heads = None
 
     def create_feed(self, mode):
+        """
+        Create feed dict and DataLoader object
+        Args:
+            mode(str): runtime mode, can be "train", "eval" or "test"
+        Return: image, labels, loader
+        """
         image_shape = deepcopy(self.image_shape)
         image_shape.insert(0, -1)
         if mode == "train":
@@ -189,9 +201,12 @@ class RecModel(object):
             inputs = image
         else:
             inputs = self.tps(image)
+        # backbone
         conv_feas = self.backbone(inputs)
+        # predict
         predicts = self.head(conv_feas, labels, mode)
         decoded_out = predicts['decoded_out']
+        # loss
         if mode == "train":
             loss = self.loss(predicts, labels)
             if self.loss_type == "attention":
@@ -211,7 +226,7 @@ class RecModel(object):
                 outputs = {'total_loss':loss, 'decoded_out':\
                     decoded_out, 'label':label}
             return loader, outputs
-
+        # export_model
         elif mode == "export":
             predict = predicts['predict']
             if self.loss_type == "ctc":
@@ -225,6 +240,7 @@ class RecModel(object):
                 ]
 
             return [image, {'decoded_out': decoded_out, 'predicts': predict}]
+        # eval or test
         else:
             predict = predicts['predict']
             if self.loss_type == "ctc":
diff --git a/ppocr/modeling/heads/rec_ctc_head.py b/ppocr/modeling/heads/rec_ctc_head.py
index 84948c2b..67adcce0 100755
--- a/ppocr/modeling/heads/rec_ctc_head.py
+++ b/ppocr/modeling/heads/rec_ctc_head.py
@@ -27,6 +27,12 @@ import numpy as np
 
 
 class CTCPredict(object):
+    """
+    CTC predict
+    Args:
+        params(object): Params from yaml file and settings from command line
+    """
+
     def __init__(self, params):
         super(CTCPredict, self).__init__()
         self.char_num = params['char_num']
diff --git a/ppocr/modeling/losses/rec_attention_loss.py b/ppocr/modeling/losses/rec_attention_loss.py
index 8d8d7c13..c8d80556 100755
--- a/ppocr/modeling/losses/rec_attention_loss.py
+++ b/ppocr/modeling/losses/rec_attention_loss.py
@@ -33,6 +33,7 @@ class AttentionLoss(object):
         predict = predicts['predict']
         label_out = labels['label_out']
         label_out = fluid.layers.cast(x=label_out, dtype='int64')
+        # calculate attention loss
         cost = fluid.layers.cross_entropy(input=predict, label=label_out)
         sum_cost = fluid.layers.reduce_sum(cost)
         return sum_cost
diff --git a/ppocr/modeling/losses/rec_ctc_loss.py b/ppocr/modeling/losses/rec_ctc_loss.py
index 3552d320..d443b8d5 100755
--- a/ppocr/modeling/losses/rec_ctc_loss.py
+++ b/ppocr/modeling/losses/rec_ctc_loss.py
@@ -30,6 +30,7 @@ class CTCLoss(object):
     def __call__(self, predicts, labels):
         predict = predicts['predict']
         label = labels['label']
+        # calculate ctc loss
         cost = fluid.layers.warpctc(
             input=predict, label=label, blank=self.char_num, norm_by_times=True)
         sum_cost = fluid.layers.reduce_sum(cost)
diff --git a/ppocr/utils/character.py b/ppocr/utils/character.py
index 97237cfa..34067f82 100755
--- a/ppocr/utils/character.py
+++ b/ppocr/utils/character.py
@@ -20,15 +20,21 @@ import sys
 
 
 class CharacterOps(object):
-    """ Convert between text-label and text-index """
+    """
+    Convert between text-label and text-index
+    Args:
+        config: config from yaml file
+    """
 
     def __init__(self, config):
         self.character_type = config['character_type']
         self.loss_type = config['loss_type']
         self.max_text_len = config['max_text_length']
+        # use the default dictionary(36 char)
         if self.character_type == "en":
             self.character_str = "0123456789abcdefghijklmnopqrstuvwxyz"
             dict_character = list(self.character_str)
+        # use the custom dictionary
         elif self.character_type in [
                 "ch", 'japan', 'korean', 'french', 'german'
         ]:
@@ -55,25 +61,27 @@ class CharacterOps(object):
             "Nonsupport type of the character: {}".format(self.character_str)
         self.beg_str = "sos"
         self.end_str = "eos"
+        # add start and end str for attention
         if self.loss_type == "attention":
             dict_character = [self.beg_str, self.end_str] + dict_character
         elif self.loss_type == "srn":
             dict_character = dict_character + [self.beg_str, self.end_str]
+        # create char dict
         self.dict = {}
         for i, char in enumerate(dict_character):
             self.dict[char] = i
         self.character = dict_character
 
     def encode(self, text):
-        """convert text-label into text-index.
-        input:
+        """
+        convert text-label into text-index.
+        Args:
             text: text labels of each image. [batch_size]
-
-        output:
+        Return:
             text: concatenated text index for CTCLoss.
                     [sum(text_lengths)] = [text_index_0 + text_index_1 + ... + text_index_(n - 1)]
-            length: length of each text. [batch_size]
         """
+        # Ignore capital
         if self.character_type == "en":
             text = text.lower()
 
@@ -86,7 +94,15 @@ class CharacterOps(object):
         return text
 
     def decode(self, text_index, is_remove_duplicate=False):
-        """ convert text-index into text-label. """
+        """
+        convert text-index into text-label.
+        Args:
+            text_index: text index for each image
+            is_remove_duplicate: Whether to remove duplicate characters,
+                                 The default is False
+        Return:
+            text: text label
+        """
         char_list = []
         char_num = self.get_char_num()
 
@@ -108,6 +124,9 @@ class CharacterOps(object):
         return text
 
     def get_char_num(self):
+        """
+        Get character num
+        """
         return len(self.character)
 
     def get_beg_end_flag_idx(self, beg_or_end):
@@ -132,6 +151,21 @@ def cal_predicts_accuracy(char_ops,
                           labels,
                           labels_lod,
                           is_remove_duplicate=False):
+    """
+    Calculate prediction accuracy
+    Args:
+        char_ops: CharacterOps
+        preds: preds result,text index
+        preds_lod: lod tensor of preds
+        labels: label of input image, text index
+        labels_lod:  lod tensor of label
+        is_remove_duplicate: Whether to remove duplicate characters,
+                                 The default is False
+    Return:
+        acc: The accuracy of test set
+        acc_num: The correct number of samples predicted
+        img_num: The total sample number of the test set
+    """
     acc_num = 0
     img_num = 0
     for ino in range(len(labels_lod) - 1):
@@ -189,6 +223,14 @@ def cal_predicts_accuracy_srn(char_ops,
 
 
 def convert_rec_attention_infer_res(preds):
+    """
+    Convert recognition attention predict result with lod information
+    Args:
+        preds: the output of the model
+    Return:
+        convert_ids: A 1-D Tensor represents all the predicted results.
+        target_lod: The lod information of the predicted results
+    """
     img_num = preds.shape[0]
     target_lod = [0]
     convert_ids = []
diff --git a/tools/eval_utils/eval_rec_utils.py b/tools/eval_utils/eval_rec_utils.py
index 4479d9df..180bfcfe 100644
--- a/tools/eval_utils/eval_rec_utils.py
+++ b/tools/eval_utils/eval_rec_utils.py
@@ -122,7 +122,9 @@ def eval_rec_run(exe, config, eval_info_dict, mode):
 
 
 def test_rec_benchmark(exe, config, eval_info_dict):
-    " Evaluate lmdb dataset "
+    """
+    eval rec benchmark
+    """
     eval_data_list = ['IIIT5k_3000', 'SVT', 'IC03_860', 'IC03_867', \
                       'IC13_857', 'IC13_1015', 'IC15_1811', 'IC15_2077', 'SVTP', 'CUTE80']
     eval_data_dir = config['TestReader']['lmdb_sets_dir']
diff --git a/tools/program.py b/tools/program.py
index 20d0b0b2..e08640b1 100755
--- a/tools/program.py
+++ b/tools/program.py
@@ -150,19 +150,20 @@ def check_gpu(use_gpu):
 def build(config, main_prog, startup_prog, mode):
     """
     Build a program using a model and an optimizer
-        1. create feeds
-        2. create a dataloader
-        3. create a model
-        4. create fetchs
-        5. create an optimizer
+        1. create a dataloader
+        2. create a model
+        3. create fetches
+        4. create an optimizer
     Args:
         config(dict): config
         main_prog(): main program
         startup_prog(): startup program
-        is_train(bool): train or valid
+        mode(str): train or valid
     Returns:
         dataloader(): a bridge between the model and the data
-        fetchs(dict): dict of model outputs(included loss and measures)
+        fetch_name_list(dict): dict of model outputs(included loss and measures)
+        fetch_varname_list(list): list of outputs' varname
+        opt_loss_name(str): name of loss
     """
     with fluid.program_guard(main_prog, startup_prog):
         with fluid.unique_name.guard():
@@ -207,8 +208,8 @@ def build_export(config, main_prog, startup_prog):
     Build input and output for exporting a checkpoints model to an inference model
     Args:
         config(dict): config
-        main_prog(): main program
-        startup_prog(): startup program
+        main_prog: main program
+        startup_prog: startup program
     Returns:
         feeded_var_names(list[str]): var names of input for exported inference model
         target_vars(list[Variable]): output vars for exported inference model
@@ -257,9 +258,14 @@ def train_eval_det_run(config,
                        train_info_dict,
                        eval_info_dict,
                        is_slim=None):
-    '''
-    main program of evaluation for detection
-    '''
+    """
+    Feed data to the model and fetch the measures and loss for detection
+    Args:
+        config: config
+        exe:
+        train_info_dict: information dict for training
+        eval_info_dict: information dict for evaluation
+    """
     train_batch_id = 0
     log_smooth_window = config['Global']['log_smooth_window']
     epoch_num = config['Global']['epoch_num']
@@ -376,9 +382,14 @@ def train_eval_rec_run(config,
                        train_info_dict,
                        eval_info_dict,
                        is_slim=None):
-    '''
-    main program of evaluation for recognition
-    '''
+    """
+    Feed data to the model and fetch the measures and loss for recognition
+    Args:
+        config: config
+        exe:
+        train_info_dict: information dict for training
+        eval_info_dict: information dict for evaluation
+    """
     train_batch_id = 0
     log_smooth_window = config['Global']['log_smooth_window']
     epoch_num = config['Global']['epoch_num']