flex-shrink: 0；
参考：flex布局下img元素被拉伸变形的有效解决办法；
Example：
<div class="v1 fx-btw">
<div class="avtar">
<img id="url" src="" alt="头像">
</div>
<div class="name" id="name">loading...
</div>
</div>
$a1 = 74px;
.avtar{
height $a1;
width $a1;
border solid .5px #e6e6e6;
border-radius 50%;
box-shadow: 0px 0px 5px 2px #ece2e2;
overflow hidden;
flex-shrink: 0;
img{
height 100%;
}
}
