1、修改数据库配置文件的编码。
打开网站根目录数据库配置文件 config.inc.php 将 charset 的值由 utf8改为 utf8mb4

/** 定义数据库参数 */
    $db = new Typecho_Db('Pdo_Mysql', 'echo_');
    $db->addServer(array (
    'host' => 'localhost',
    'user' => 'user',
    'password' => 'password',
    'charset' => 'utf8mb4', //修改这一参数
    'port' => '3306', 
    'database' => 'echo',
    ), Typecho_Db::READ | Typecho_Db::WRITE);

    Typecho_Db::set($db);

2、修改数据库编码。

alter table typecho_comments convert to character set utf8mb4 collate utf8mb4_general_ci;
alter table typecho_contents convert to character set utf8mb4 collate utf8mb4_general_ci;
alter table typecho_fields convert to character set utf8mb4 collate utf8mb4_general_ci;
alter table typecho_metas convert to character set utf8mb4 collate utf8mb4_general_ci;
alter table typecho_options convert to character set utf8mb4 collate utf8mb4_general_ci;
alter table typecho_relationships convert to character set utf8mb4 collate utf8mb4_general_ci;
alter table typecho_users convert to character set utf8mb4 collate utf8mb4_general_ci;