window.onload = function () {
  var c = new Vue({
  el : '#box',
  data : {
   url : 'https://img6.bdstatic.com/img/image/smallpic/weijupaishefensetu.jpg'
  }
  });
 }

<div id="box">
  <img src="{{url}}" alt=""/>
</div>

window.onload = function () {
  var c = new Vue({
  el : '#box',
  data : {
   url : 'https://img6.bdstatic.com/img/image/smallpic/weijupaishefensetu.jpg'
  }
  });
 }
 
<div id="box">
 <img v-bind:src="url" alt=""/>
</div>

window.onload = function () {
  var c = new Vue({
  el : '#box',
  data : {
   url : 'https://img6.bdstatic.com/img/image/smallpic/weijupaishefensetu.jpg'
  }
  });
 }

<div id="box">
 <img :src="url" alt=""/>
 </div>

window.onload = function () {
  var c = new Vue({
  el : '#box',
  data : {
   url : 'https://img6.bdstatic.com/img/image/smallpic/weijupaishefensetu.jpg',
   w : '400px',
   t : '这是一张百度图片'
  }
  });
 }

<div id="box">
 <img :src="url" :width="w" :title="t" alt=""/>
</div>