diff --git a/logs/conn.go b/logs/conn.go
index eed9ae2f..77bf4de8 100644
--- a/logs/conn.go
+++ b/logs/conn.go
@@ -29,6 +29,9 @@ func NewConn() LoggerInterface {
 // init connection writer with json config.
 // json config only need key "level".
 func (c *ConnWriter) Init(jsonconfig string) error {
+	if len(jsonconfig) == 0 {
+		return nil
+	}
 	err := json.Unmarshal([]byte(jsonconfig), c)
 	if err != nil {
 		return err
diff --git a/logs/file.go b/logs/file.go
index 9400e04d..c9f81df5 100644
--- a/logs/file.go
+++ b/logs/file.go
@@ -90,6 +90,9 @@ func NewFileWriter() LoggerInterface {
 //	"rotate":true
 //	}
 func (w *FileLogWriter) Init(jsonconfig string) error {
+	if len(jsonconfig) == 0 {
+		return nil
+	}
 	err := json.Unmarshal([]byte(jsonconfig), w)
 	if err != nil {
 		return err
diff --git a/logs/smtp.go b/logs/smtp.go
index 19296887..ec1c61ca 100644
--- a/logs/smtp.go
+++ b/logs/smtp.go
@@ -38,6 +38,9 @@ func NewSmtpWriter() LoggerInterface {
 //		"level":LevelError
 //	}
 func (s *SmtpWriter) Init(jsonconfig string) error {
+	if len(jsonconfig) == 0 {
+		return nil
+	}
 	err := json.Unmarshal([]byte(jsonconfig), s)
 	if err != nil {
 		return err