diff --git a/fileutil/file.go b/fileutil/file.go
index 357b459..7db1685 100644
--- a/fileutil/file.go
+++ b/fileutil/file.go
@@ -453,3 +453,35 @@ func ReadCsvFile(filepath string) ([][]string, error) {
 
 	return records, nil
 }
+
+// WriteStringToFile write string to target file.
+// Play: todo
+func WriteStringToFile(filepath string, content string, append bool) error {
+	flag := os.O_RDWR | os.O_CREATE
+	if append {
+		flag = flag | os.O_APPEND
+	}
+
+	f, err := os.OpenFile(filepath, flag, 0644)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	_, err = f.WriteString(content)
+	return err
+}
+
+// WriteBytesToFile write bytes to target file.
+// Play: todo
+func WriteBytesToFile(filepath string, content []byte) error {
+	f, err := os.OpenFile(filepath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
+	if err != nil {
+		return err
+	}
+
+	defer f.Close()
+
+	_, err = f.Write(content)
+	return err
+}
diff --git a/fileutil/file_example_test.go b/fileutil/file_example_test.go
index e883384..6d7e147 100644
--- a/fileutil/file_example_test.go
+++ b/fileutil/file_example_test.go
@@ -285,3 +285,59 @@ func ExampleReadCsvFile() {
 	// [[Bob  12  male] [Duke  14  male] [Lucy  16  female]]
 	// <nil>
 }
+
+func ExampleWriteStringToFile() {
+	filepath := "./test.txt"
+
+	file, err := os.Create(filepath)
+	if err != nil {
+		return
+	}
+
+	defer file.Close()
+
+	err = WriteStringToFile(filepath, "hello", true)
+	if err != nil {
+		return
+	}
+
+	content, err := ReadFileToString(filepath)
+	if err != nil {
+		return
+	}
+
+	os.Remove(filepath)
+
+	fmt.Println(content)
+
+	// Output:
+	// hello
+}
+
+func ExampleWriteBytesToFile() {
+	filepath := "./bytes.txt"
+
+	file, err := os.Create(filepath)
+	if err != nil {
+		return
+	}
+
+	defer file.Close()
+
+	err = WriteBytesToFile(filepath, []byte("hello"))
+	if err != nil {
+		return
+	}
+
+	content, err := ReadFileToString(filepath)
+	if err != nil {
+		return
+	}
+
+	os.Remove(filepath)
+
+	fmt.Println(content)
+
+	// Output:
+	// hello
+}
diff --git a/fileutil/file_test.go b/fileutil/file_test.go
index 60ddbc5..acdec64 100644
--- a/fileutil/file_test.go
+++ b/fileutil/file_test.go
@@ -296,3 +296,68 @@ func TestReadCsvFile(t *testing.T) {
 	assert.Equal(3, len(content[0]))
 	assert.Equal("Bob", content[0][0])
 }
+
+func TestWriteStringToFile(t *testing.T) {
+	assert := internal.NewAssert(t, "TestWriteStringToFile")
+
+	filepath := "./test.txt"
+
+	file, err := os.Create(filepath)
+	if err != nil {
+		t.Fail()
+	}
+
+	defer file.Close()
+
+	err = WriteStringToFile(filepath, "hello", false)
+	if err != nil {
+		t.Fail()
+	}
+
+	content1, err := ReadFileToString(filepath)
+	if err != nil {
+		t.Fail()
+	}
+
+	err = WriteStringToFile(filepath, " world", true)
+	if err != nil {
+		t.Fail()
+	}
+
+	content2, err := os.ReadFile(filepath)
+	if err != nil {
+		t.Fail()
+	}
+
+	assert.Equal("hello", content1)
+	assert.Equal("hello world", string(content2))
+
+	os.Remove(filepath)
+}
+
+func TestWriteBytesToFile(t *testing.T) {
+	assert := internal.NewAssert(t, "TestWriteBytesToFile")
+
+	filepath := "./bytes.txt"
+
+	file, err := os.Create(filepath)
+	if err != nil {
+		t.Fail()
+	}
+
+	defer file.Close()
+
+	err = WriteBytesToFile(filepath, []byte("hello"))
+	if err != nil {
+		t.Fail()
+	}
+
+	content, err := os.ReadFile(filepath)
+	if err != nil {
+		t.Fail()
+	}
+
+	assert.Equal("hello", string(content))
+
+	os.Remove(filepath)
+}