diff --git a/word/word.go b/word/word.go
new file mode 100644
index 0000000..20d80c7
--- /dev/null
+++ b/word/word.go
@@ -0,0 +1,51 @@
+/*
+ * @Date: 2021-06-10 14:33:29
+ * @LastEditors: viletyy
+ * @LastEditTime: 2021-06-10 14:40:55
+ * @FilePath: /yolk/word/word.go
+ */
+package word
+
+import (
+	"strings"
+	"unicode"
+)
+
+// 全部转为大写
+func ToUpper(s string) string {
+	return strings.ToUpper(s)
+}
+
+// 全部转为小写
+func ToLower(s string) string {
+	return strings.ToLower(s)
+}
+
+// 下划线转大写驼峰
+func UnderscoreToUpperCamelCase(s string) string {
+	s = strings.Replace(s, "_", " ", -1)
+	s = strings.Title(s)
+	return strings.Replace(s, " ", "", -1)
+}
+
+// 下划线转小写驼峰
+func UnderscoreToLowerCamelCase(s string) string {
+	s = UnderscoreToUpperCamelCase(s)
+	return string(unicode.ToLower(rune(s[0]))) + s[1:]
+}
+
+// 驼峰转下划线
+func CamelCaseToUnderscore(s string) string {
+	var output []rune
+	for i, r := range s {
+		if i == 0 {
+			output = append(output, unicode.ToLower(r))
+			continue
+		}
+		if unicode.IsUpper(r) {
+			output = append(output, '_')
+		}
+		output = append(output, unicode.ToLower(r))
+	}
+	return string(output)
+}