在試了很多次了，終於搞定了，上程式碼吧。（我用的是jquery的ajax，不是原生的）

js程式碼：

<script>
    $(document).ready(function () {
        getcomment();
$('.comment-box button').click(function () {
            var comment_text = $('.comment-box textarea').val();
$.ajax({
                type: 'POST',
url: '/bbs/article/{{ article_list
 
.id }}/comment/',
data: {comment: comment_text},
success:function (callback) {
                    var data = $.parseJSON(callback);
$('.callback').html(data.result);
if(data.result === 'successfully') {
                        getcomment();
}
                }
            })
        });
});
function 
 
getcomment() {
        $.ajax({
            type: 'GET',
url: '/bbs/article/{{ article_list.id }}/get_comment/',
success:function (call) {
                var datas = $.parseJSON(call);
$('.comment-list').html(datas.answer);
}
        })
    }
</script>

html模板（用到是bootstrap模板）：

 <div class="row">
         <div class="comment-list" style="margin-left: 10px">
         </div>
     </div>
     <div class="row">
   <article class="col-xs-12">
                 <h4>請評論：</h4>
                 <div class="comment-box">
                     <textarea class="form-control" rows="3"></textarea>
                     <span class="callback"></span><button type="submit" class="btn btn-success pull-right" style="max-width: 5px;">評論</button>
                 </div>
   </article>
</div>
     <hr>

檢視函式：

@csrf_exempt
def comment(request,article_id):
if request.method == 'POST':
comments = request.POST['comment']
        if len(comments) < 5:
result = u'評論數需大於5'
return HttpResponse(json.dumps({'result': result}))
        else:
result = 'successfully'
Comment.objects.create(content= comments, article_id=article_id)
            return HttpResponse(json.dumps({'result': result}))

def get_comment(request, article_id):
article_list = get_object_or_404(Article, id=article_id)
    comments = article_list.comment_set.all()
    html = ''
for i in comments:
ele = '<div class="row"><article class="col-xs-12"><p class="pull-right"><span class="label label-default">作者:' + 'i.user' + '</span></p><p>' + i.content + '<ul class="list-inline"><li><a href="#"></a></li></ul></article></div><hr>'
html += ele
    return HttpResponse(json.dumps({'answer': html}))

後臺獲取評論的函式。

最後將textarea的值清空：

function resettext() {
    $('.form-control').val('');
}

這樣就可以實現了