I gathered some Chinese stuff:

    (setq gnus-default-charset 'cn-gb-2312)
    (setq gnus-group-name-charset-group-alist (quote ((".*" . gb2312))))
    (setq gnus-group-posting-charset-alist
          '(("^\\(cn\\)\\.[^,]*\\(,[ 	\n]*\\(cn\\)\\.[^,]*\\)*$" gb2312 (gb2312))
            (message-this-is-mail nil nil)
            (message-this-is-news nil t)))
    Some mail clients encode Chinese by using gb18030, x-gbk, etc, which are
    unknown to Emacs at present. But here is a workaround for them, suppose
    your Emacs support gb2312 charsets:
        ;; A workaround for unsupported charsets
        (define-coding-system-alias 'gb18030 'gb2312)
        (define-coding-system-alias 'x-gbk 'gb2312)
    This will make most Chinese readable as long as there are few Chinese
    characters that are beyond gb2312.

CategoryInternationalization CategoryGnus