option{

     padding:5px 0;
   }

示例填充Jsfiddle

.dis option{
 padding:5px 0;

 }

HTML

<select class="dis">
  <option>1erwer</option>
  <option>2wwerwer</option>
  <option>3werwer</option>
  <option>4werwer</option>
  <option>5wrwer</option>
</select>

增加两个选项之间的空间是不可能的

but there is a tricky way

<select class="dis">
  <option>1erwer</option>
  <option>2wwerwer</option>
  <option>3werwer</option>
  <option disabled="disabled" ></option> <---trick 
  <option>3werwer</option>
</select>