<div class="center">
  我是多行文字，我是多行文字，我是多行文字
</div>

.center {
  width: 100px;
  height: 100px;
  padding: 10px;
  border: 1px solid #ccc;
  margin: 20px auto;
  word-break: break-all;


  display: -webkit-box;
  -webkit-box-orient: horizontal;
  -webkit-box-pack: center;
  -webkit-box-align: center;
  
  display: -moz-box;
  -moz-box-orient: horizontal;
  -moz-box-pack: center;
  -moz-box-align: center;
  
  display: -o-box;
  -o-box-orient: horizontal;
  -o-box-pack: center;
  -o-box-align: center;
  
  display: -ms-box;
  -ms-box-orient: horizontal;
  -ms-box-pack: center;
  -ms-box-align: center;
  
  display: box;
  box-orient: horizontal;
  box-pack: center;
  box-align: center;
}