perl: warning: Setting locale failed

perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
        LANGUAGE = "zh_CN:zh",
        LC_ALL = (unset),
        LC_MESSAGES = "zh_CN.UTF-8",
        LC_COLLATE = "zh_CN.UTF-8",
        LC_CTYPE = "zh_CN.UTF-8",
        LANG = "en_US"
    are supported and installed on your system.

perl: warning: Falling back to the standard locale ("C").

export LC_ALL=C