SOURCE

var ComponentA={
    template:' <div>我是ComponentA</div>'
}
var ComponentB={
  template:' <div>我是ComponentB</div>'
}
var ComponentC={
  template:' <div>ComponenC下的<component-a></component-a></div> ',
   components: {
    'component-a': ComponentA
  },
}


new Vue({
  el: '#app',
  components: {
    'component-a': ComponentA,
    'component-b': ComponentB,
    'component-c': ComponentC,
  }
})

<script src="https://unpkg.com/vue/dist/vue.js"></script>
<div id="app">
 <component-a></component-a>
  <component-b></component-b>
  <component-c></component-c>
</div>