首先需要在主题的function.php文件里添加一段函数： 

< ?php 
function fail($s) { 
header('HTTP/1.0 500 Internal Server Error'); 
echo $s; 
exit; 
} 
function ajax_comment(){ 
if($_POST['action'] == 'ajax_comment') { 
global $wpdb, $db_check; 
// Check DB 
if(!$wpdb->dbh) { 
echo('Our database has issues. Try again later.'); 
die(); 
} 
nocache_headers(); 
$comment_post_ID = (int) $_POST['comment_post_ID']; 
$status = $wpdb->get_row("SELECT post_status, comment_status FROM $wpdb->posts WHERE ID = '$comment_post_ID'"); 
if ( empty($status->comment_status) ) { 
do_action('comment_id_not_found', $comment_post_ID); 
fail('The post you are trying to comment on does not currently exist in the database.'); 
} elseif ( 'closed' == $status->comment_status ) { 
do_action('comment_closed', $comment_post_ID); 
fail('Sorry, comments are closed for this item.'); 
} elseif ( in_array($status->post_status, array('draft', 'pending') ) ) { 
do_action('comment_on_draft', $comment_post_ID); 
fail('The post you are trying to comment on has not been published.'); 
} 
$comment_author = trim(strip_tags($_POST['author'])); 
$comment_author_email = trim($_POST['email']); 
$comment_author_url = trim($_POST['url']); 
$comment_content = trim($_POST['comment']); 
// If the user is logged in 
$user = wp_get_current_user(); 
if ( $user->ID ) { 
$comment_author = $wpdb->escape($user->display_name); 
$comment_author_email = $wpdb->escape($user->user_email); 
$comment_author_url = $wpdb->escape($user->user_url); 
if ( current_user_can('unfiltered_html') ) { 
if ( wp_create_nonce('unfiltered-html-comment_' . $comment_post_ID) != $_POST['_wp_unfiltered_html_comment'] ) { 
kses_remove_filters(); // start with a clean slate 
kses_init_filters(); // set up the filters 
} 
} 
} else { 
if ( get_option('comment_registration') ) 
fail('Sorry, you must be logged in to post a comment.'); 
} 
$comment_type = ''; 
if ( get_option('require_name_email') && !$user->ID ) { 
if ( 6> strlen($comment_author_email) || '' == $comment_author ) 
fail('Sorry: please fill the required fields (name, email).'); 
elseif ( !is_email($comment_author_email)) 
fail('Sorry: please enter a valid email address.'); 
} 
if ( '' == $comment_content ) 
fail('Sorry: please type a comment.'); 
// Simple duplicate check 
$dupe = "SELECT comment_ID FROM $wpdb->comments WHERE comment_post_ID = '$comment_post_ID' AND ( comment_author = '$comment_author' "; 
if ( $comment_author_email ) $dupe .= "OR comment_author_email = '$comment_author_email' "; 
$dupe .= ") AND comment_content = '$comment_content' LIMIT 1"; 
if ( $wpdb->get_var($dupe) ) { 
fail('Duplicate comment detected; it looks as though you\'ve already said that!'); 
} 
$commentdata = compact('comment_post_ID', 'comment_author', 'comment_author_email', 'comment_author_url', 'comment_content', 'comment_type', 'user_ID'); 
if( !$user->ID ){ 
$result_set = $wpdb->get_results("SELECT display_name, user_email FROM $wpdb->users WHERE display_name = '" . $comment_author . "' OR user_email = '" . $comment_author_email . "'"); 
if ($result_set) { 
if ($result_set[0]->display_name == $comment_author){ 
fail( __('Error: you are not allowed to use the nickname that you entered.if you are the administrator you hava to login to comment.','philna2') ); 
} else { 
fail( __('Error: you are not allowed to use the email that you entered.if you are the administrator you hava to login to comment.','philna2') ); 
} 
} 
} 
$comment_id = wp_new_comment( $commentdata ); 
$comment = get_comment($comment_id); 
if( !$user->ID ){ 
setcookie('comment_author_' . COOKIEHASH, $comment->comment_author, time() + 30000000, COOKIEPATH, COOKIE_DOMAIN); 
setcookie('comment_author_email_' . COOKIEHASH, $comment->comment_author_email, time() + 30000000, COOKIEPATH, COOKIE_DOMAIN); 
setcookie('comment_author_url_' . COOKIEHASH, clean_url($comment->comment_author_url), time() + 30000000, COOKIEPATH, COOKIE_DOMAIN); 
} 
@header('Content-type: ' . get_option('html_type') . '; charset=' . get_option('blog_charset')); 
?> 
//这里需要粘贴你的评论框架代码，不过相关的调用代码有所变化： 
//评论ID：$comment->comment_ID 
//评论者名字：$comment->comment_author 
//判断评论者是否填写了网站地址：$comment->get_comment_author_url 
//评论者URL：$comment->comment_author_url 
//评论时间：mysql2date(__('F jS, Y'),$comment->comment_date) 
//评论者e-mail：$comment->comment_author_email 
//评论内容$comment->comment_content 
< ?php 
die(); 
} 
} 
add_action('init', 'ajax_comment'); 
//添加AJAX评论钩子 
?> 

如果处理评论内容里的换行符的话，$comment->comment_content需做以下处理： 

< ?php 
$aj_order = array("\r\n", "\n", "\r"); 
$aj_comment_content = str_replace($aj_order,'
',$comment->comment_content); 
echo $aj_comment_content; 
?> 

用jQuery写提交评论时的脚本，这也是关键的部分： 

jQuery(document).ready(function() { 
if (jQuery('#commentform').length) { 
jQuery('#commentform').submit(function(){ //ID为 commentform 的表单提交时发生的函数，也就是整个留言输入框 form 的ID。 
var ajaxCommentsURL = window.location.href; 
jQuery.ajax({ 
url: ajaxCommentsURL, 
data: jQuery('#commentform').serialize()+'&action=ajax_comment', 
type: 'POST', 
beforeSend: function() { 
jQuery('#commenterror').hide(); 
var submit='<div id="commentload"img/spinner.gif") no-repeat scroll 0 50%;margin: 0 auto;">Submitting Comment...</div>'; //创建名为 submit 的字符串，稍后插入，这里的样式大家自己根据需要定义，那个背景图片自己去下哈。 
var error='<div id="commenterror">Posted comment fail.</div>'; //创建名为 error 的字符串 
jQuery('#comments').after(submit); // 在ID为 comments 的元素后插入刚定义的 submit 
jQuery('#comments').after(error); // 同样插入刚定义的 error 
jQuery('#commentload').slideDown(); // 让submit 向下滑出 
}, 
error: function(request) { //发生错误时 
jQuery('#commentload').hide(); //隐藏 submit 
jQuery('#commenterror').show("slow").html(request.responseText); //显示 error 
}, 
success: function(data) { 
jQuery('textarea').each(function(){ 
this.value=''; 
}); 
jQuery('#commenterror').hide().html(); 
if (!jQuery('#thecomments').length) { 
jQuery('#pinglist').before('<ol id="thecomments"></ol>');} 
jQuery('#thecomments').append(data); //向ID为 thecomments 的元素添加数据，也就是整个 ol 或 ul 
var new_comment = jQuery('#thecomments li:last').hide(); //让最新添加的数据隐藏 
new_comment.slideDown(1000); //再显示，这里是为了实现滑出的效果，不想要也可以直接显示 
jQuery('#commentform:input').attr('disabled', true); 
jQuery('#commentload').slideUp("slow"); 
jQuery('#messagebox').slideUp("slow"); //这是针对我模版而加的，因为我模版在没有留言时会有个 nocomment 的元素，我要让添加一条留言后他自动隐藏，要不然会矛盾，呵呵，这个可以自行选择要或不要 
setTimeout(function() { 
jQuery('#commentform:input').removeAttr('disabled'); 
}, 10000); //这里是设置10秒之后才可以再次留言，自行设置，单位毫秒。 
} 
}); 
return false; 
} ); 
}}) 

注意： 
脚本里的对象ID要对应主题里的评论相关框架的ID。 
后续步骤： 
为commentload，commenterror写CSS。 
有待完善的地方： 
AJAX提交后的评论序号显示为1。