Thank you all for your comments and advices.

I feel is not flash problem. that is lens quality , I think that is not original lens and without ED .

Try to use flash or reflector to get her face sharp and clear. Now it's too dim. Learn how to use flash. Remember: flash can also be used at sunny day; eg. if U take photo with backlight, or under a shade.

多謝指教

光暗處理有待改善，主體背景反差太大，應為主體補光而不應完全放棄背景