diff --git a/http.go b/http.go
index 005d4ea..166167c 100644
--- a/http.go
+++ b/http.go
@@ -122,11 +122,10 @@ func WriteBodyByMultipartFormData(params ...any) (*bytes.Buffer, string, error)
 			continue
 		}
 		h := make(textproto.MIMEHeader)
-		h.Set("Content-Disposition",
-			fmt.Sprintf(`form-data; name="%s"; filename="%s"`,
-				escapeQuotes(fieldname), escapeQuotes(fieldname)))
 		if rx.Kind() == reflect.Pointer && rx.Elem().Kind() == reflect.Struct { // 使用 json 编码
-			h.Set("Content-Type", "application/octet-stream")
+			h.Set("Content-Disposition",
+				fmt.Sprintf(`form-data; name="%s"`, escapeQuotes(fieldname)))
+			h.Set("Content-Type", "application/json")
 			r, err := w.CreatePart(h)
 			if err != nil {
 				return nil, "", err
@@ -140,6 +139,9 @@ func WriteBodyByMultipartFormData(params ...any) (*bytes.Buffer, string, error)
 		switch o := x.(type) {
 		case string:
 			if strings.HasPrefix(o, "file:///") { // 是文件路径
+				h.Set("Content-Disposition",
+					fmt.Sprintf(`form-data; name="%s"; filename="%s"`,
+						escapeQuotes(fieldname), escapeQuotes(fieldname)))
 				h.Set("Content-Type", "application/octet-stream")
 				r, err := w.CreatePart(h)
 				if err != nil {
@@ -157,6 +159,9 @@ func WriteBodyByMultipartFormData(params ...any) (*bytes.Buffer, string, error)
 				continue
 			}
 			if strings.HasPrefix(o, "base64://") { // 是 base64
+				h.Set("Content-Disposition",
+					fmt.Sprintf(`form-data; name="%s"; filename="%s"`,
+						escapeQuotes(fieldname), escapeQuotes(fieldname)))
 				h.Set("Content-Type", "application/octet-stream")
 				r, err := w.CreatePart(h)
 				if err != nil {
@@ -169,6 +174,9 @@ func WriteBodyByMultipartFormData(params ...any) (*bytes.Buffer, string, error)
 				continue
 			}
 			if strings.HasPrefix(o, "base16384://") { // 是 base16384
+				h.Set("Content-Disposition",
+					fmt.Sprintf(`form-data; name="%s"; filename="%s"`,
+						escapeQuotes(fieldname), escapeQuotes(fieldname)))
 				h.Set("Content-Type", "application/octet-stream")
 				r, err := w.CreatePart(h)
 				if err != nil {
@@ -180,6 +188,9 @@ func WriteBodyByMultipartFormData(params ...any) (*bytes.Buffer, string, error)
 				}
 				continue
 			}
+			h.Set("Content-Disposition",
+				fmt.Sprintf(`form-data; name="%s"`, escapeQuotes(fieldname)))
+			h.Set("Content-Type", "application/json")
 			r, err := w.CreatePart(h)
 			if err != nil {
 				return nil, "", err
@@ -190,6 +201,9 @@ func WriteBodyByMultipartFormData(params ...any) (*bytes.Buffer, string, error)
 			}
 			continue
 		case []byte:
+			h.Set("Content-Disposition",
+				fmt.Sprintf(`form-data; name="%s"; filename="%s"`,
+					escapeQuotes(fieldname), escapeQuotes(fieldname)))
 			h.Set("Content-Type", "application/octet-stream")
 			r, err := w.CreatePart(h)
 			if err != nil {
@@ -201,6 +215,9 @@ func WriteBodyByMultipartFormData(params ...any) (*bytes.Buffer, string, error)
 			}
 			continue
 		default:
+			h.Set("Content-Disposition",
+				fmt.Sprintf(`form-data; name="%s"`, escapeQuotes(fieldname)))
+			h.Set("Content-Type", "application/json")
 			r, err := w.CreatePart(h)
 			if err != nil {
 				return nil, "", err