typecho默认使用utf-8编码，utf-8使用3个字节进行存储，而emoji有4个字节，因此将utf-8转换为utf8mb4即可解决
注意：mysql的版本必须为v5.5.3或更高
在数据库执行以下查询：
alter table typecho_comments convert to character set utf8mb4 collate utf8mb4_unicode_ci; alter table typecho_contents convert to character set utf8mb4 collate utf8mb4_unicode_ci; alter table typecho_fields convert to character set utf8mb4 collate utf8mb4_unicode_ci; alter table typecho_metas convert to character set utf8mb4 collate utf8mb4_unicode_ci; alter table typecho_options convert to character set utf8mb4 collate utf8mb4_unicode_ci; alter table typecho_relationships convert to character set utf8mb4 collate utf8mb4_unicode_ci; alter table typecho_users convert to character set utf8mb4 collate utf8mb4_unicode_ci;
注意把上面数据表的前缀typecho改成你的前缀！！！
修改config.inc.php：
$db->addServer(array ( 'host' => 'localhost', 'user' => 'username', 'password' => 'password', 'charset' => 'utf8mb4', //修改此行 'port' => '3306', 'database' => 'typecho', ), Typecho_Db::READ | Typecho_Db::WRITE);
大功告成