还是自己慢慢搞定了。
<script type="text/javascript">
        $(function(){
            $(".sytj").click(function(){
                var formData = $(".index_form").serialize();
                var url = "/index.php/p/form-content-add.html?mid=3";
                $.post(url,formData,function(res){
                    if(res.code==0){
                        layer.msg("表单已提交,感谢你参与!");
                        $(".index_form").hide(1000);
                    }else{
                        layer.alert(res.msg);
                    }
                });
            });
        })
        </script>
指定表格模型mid=3后提交，返回当前页面。

路过坐等