找到根目录下的/var/Typecho/Common.php文件大概920行左右，替换为如下

       public static function gravatarUrl($mail, $size, $rating, $default, $isSecure = false)
    {
        if (defined('__TYPECHO_GRAVATAR_PREFIX__')) {
            $url = __TYPECHO_GRAVATAR_PREFIX__;
        } else {
            $url = $isSecure ? 'https://secure.gravatar.com' : 'http://www.gravatar.com';
            $url .= '/avatar/';
        }

        if (!empty($mail)) {
            $url .= md5(strtolower(trim($mail)));
        }

        $url .= '?s=' . $size;
        $url .= '&r=' . $rating;
        $url .= '&d=' . $default;

        return $url;
    }.

替换成

       public static function gravatarUrl($mail, $size, $rating, $default, $isSecure = false)
    {
        if (defined('__TYPECHO_GRAVATAR_PREFIX__')) {
            $url = __TYPECHO_GRAVATAR_PREFIX__;
        } else {
            $url = $isSecure ? '你的头像地址' : '备用头像地址';
        }
        return $url;
    }