直接上代码

.layui-form-label.layui-required:after{

        content:"*";

        color:red;

        position: absolute;

        top:5px;

        left:15px;

    }

<div class="layui-form">

<div class="layui-form-item">

<label class="layui-form-label layui-required">消息标题：</label>

<div class="layui-input-block">

         <input type="text" name="name" autocomplete="off" placeholder="请输入消息标题" class="layui-input">

</div>

</div>

</div>

效果