纯css，div隐藏滚动条，保留鼠标滚动效果。

.nav_wrap{
    height: 400px;
    width: 200px;
    overflow: hidden;
    border: 1px solid #ccc;
    margin: 20px auto;
}
.nav_ul{
    height: 100%;
    width: 220px;
    overflow-y: auto;
    overflow-x: hidden;
}
.nav_li{
    border: 1px solid #ccc;
    margin: -1px;
    height: 40px;
    line-height: 40px;
    text-align: center;
    font-size: 12px;
    width: 200px;
}
.btn_wrap{
    text-align: center;
}

<div class= "nav_wrap">
    <ul class= "nav_ul">
        <li class="nav_li">我是菜单1</li>
        <li class="nav_li">我是菜单2</li>
    </ul>
</div>
https://blog.csdn.net/liusaint1992/article/details/51277751