<style type="text/css">
    ul, li {
        margin: 0;
        padding: 0;
    }

    ul {
        height: 300px;
        line-height: 0;
        font-size: 0;
        -ms-writing-mode: tb-lr;
        -webkit-writing-mode: vertical-lr;
        writing-mode: vertical-lr;
    }

    li {
        display: inline-block;
        width: 100px;
        height: 100px;
        border-radius: 10px;
        line-height: 100px;
        text-align: center;
        font-size: 20px;
        color: #fff;
        background: #ff0000;
        -ms-writing-mode: lr-tb;
        -webkit-writing-mode: horizontal-tb;
        writing-mode: horizontal-tb;
    }
</style>
<ul>
    <li>1</li>
    <li>2</li>
    <li>3</li>
    <li>4</li>
    <li>5</li>
    <li>6</li>
    <li>7</li>
    <li>8</li>
    <li>9</li>
    <li>10</li>
</ul>

IE8及以上、现代浏览器支持.

什么都不需要，inline-block 本来就会自动换行啊

https://jsfiddle.net/f48jewqa/1/

兼容性比 flex 好点
（兼容 IE9 及以上）
稍难维护。
但不用 Hack 就可以在 IE9-IE11 中保持一个样子。
其实用 JavaScript 更好……

.itemContainer {
    width: 150px;overflow: auto;
    padding-left: 40px;
    -ms-transform: rotate(270deg) matrix(-1,0,0,1,0,0);
    transform: rotate(270deg) matrix(-1,0,0,1,0,0);
    font-size: 13px;color: white;
    list-style: none;
    font-family: "Roboto", Roboto;
}
.item {
    -ms-transform: rotate(270deg) matrix(-1,0,0,1,0,0);
    transform: rotate(270deg) matrix(-1,0,0,1,0,0);
    height: 20px;width: 30px;margin: 10px 0;
    background: #039be5;
    text-align: center;line-height: 20px;
    display: inline-block;
}

<ul class="itemContainer">
    <li class="item">1</li>
    <li class="item">2</li>
    <li class="item">3</li>
    <li class="item">4</li>
    <li class="item">5</li>
    <li class="item">6</li>
    <li class="item">7</li>
    <li class="item">8</li>
</ul>

css有个分列的column属性

.itemContainer {
    width:100px;
    column-count:2;
}
.item {
    height: 20px;
    width: 30px;
    margin: 10px 0;
    background: #039be5;
    text-align: center;
    line-height: 20px;
    display: inline-block;
}