diff --git a/google_drive.go b/google_drive.go
index 7ae517a..28f19c6 100644
--- a/google_drive.go
+++ b/google_drive.go
@@ -45,18 +45,23 @@ func NewGoogleDrive(apiKey string) (*GoogleDrive, error) {
 	return &ggdrive, nil
 }
 
-func (g GoogleDrive) GetFilesByFolderID(folderID string) ([]GoogleDriveFile, error) {
+func (g GoogleDrive) GetFilesByFolderID(folderID string, mimeType []string) ([]GoogleDriveFile, error) {
 	var (
 		result = make([]GoogleDriveFile, 0)
 	)
 
-	res, err := getfilelist.Folder(folderID).Fields("files(name,id)").Do(g.svc)
+	chain := getfilelist.Folder(folderID).Fields("files(id,name)")
+	if len(mimeType) > 0 {
+		chain.MimeType(mimeType)
+	}
+
+	res, err := chain.Do(g.svc)
 	if err != nil {
 		err := fmt.Errorf("error when fetch folder %s: %s", folderID, err.Error())
 		return result, err
 	}
 
-	// if there is more than 1 subfolder
+	// if there is more than 1 sub folder
 	if len(res.FileList) != 1 {
 		err := fmt.Errorf("folder %s have more than 1 subfolder", folderID)
 		return result, err