If I change font configuration to:
(set-frame-font "Monaco-10")
(set-fontset-font (frame-parameter nil 'font)
          'han (font-spec :family "Microsoft Yahei" :size 16))
(set-fontset-font (frame-parameter nil 'font)
          'symbol (font-spec :family "Microsoft Yahei" :size 16))
(set-fontset-font (frame-parameter nil 'font)
          'cjk-misc (font-spec :family "Microsoft Yahei" :size 16))
(set-fontset-font (frame-parameter nil 'font)
          'bopomofo (font-spec :family "Microsoft Yahei" :size 16))

Emacs will use the right Chinese font.

On Wed, Jun 11, 2008 at 7:27 PM, Jason Rumney <jasonr@gnu.org> wrote:

> Kevin Yu wrote:
> > Here's my font related configuration
> >
> > (set-language-environment "chinese-gb18030")
> > (set-frame-font "Monaco-10")
> > (set-fontset-font (frame-parameter nil 'font)
> > 'han '("Microsoft Yahei"."unicode-bmp"))
> > (set-fontset-font (frame-parameter nil 'font)
> > 'symbol '("Microsoft Yahei"."unicode-bmp"))
> > (set-fontset-font (frame-parameter nil 'font)
> > 'cjk-misc '("Microsoft Yahei"."unicode-bmp"))
> > (set-fontset-font (frame-parameter nil 'font)
> > 'bopomofo '("Microsoft Yahei"."unicode-bmp"))
>
> Thanks, I can reproduce the original problem with these settings.
>
> For the other problem (a different font being used even when Chinese
> characters display), you may need to use the localized font name of
> Microsoft Yahei. Maybe the following will tell you what that is, as I
> expect that Windows recognizes the ASCII names for fonts even if it
> outputs the localized name.
>
> (list-fonts (font-spec :family "Microsoft Yahei"))
>
>
>