.layui-form-label.required:before{
    top: 8px;
    right: 8px;
    color: red;
    content: '*';
    font-weight: 900;
    line-height: 1.8em;
}

<div class="layui-form-item">
    <label class="layui-form-label required">标题：</label>
    <div class="layui-input-block">
        <input type="text" name="title" lay-verify="required|length" lay-reqText="标题不能为空" placeholder="请输入标题" class="layui-input" name="desc" class="layui-textarea">
    </div>
</div>