<div class="modal show">
 <div class="modal-dialog">
  <div class="modal-content">
   <div class="modal-header">
    <button type="button" class="close" data-dismiss="modal"><span aria-hidden="true">×</span><span
      class="sr-only">Close</span></button>
    <h4 class="modal-title">模态弹出窗标题</h4>
   </div>
   <div class="modal-body">
    <p>模态弹出窗主体</p>
   </div>
   <div class="modal-footer">
    <button type="button" class="btn btn-default" data-dismiss="modal">取消</button>
    <button type="button" class="btn btn-primary">确定</button>
   </div>
  </div>
 </div>
</div>

.modal-content {
 position: relative;
 background-color: #fff;
 -webkit-background-clip: padding-box;
   background-clip: padding-box;
 border: 1px solid #999;
 border: 1px solid rgba(0, 0, 0, .2);
 border-radius: 6px;
 outline: 0;
 -webkit-box-shadow: 0 3px 9px rgba(0, 0, 0, .5);
   box-shadow: 0 3px 9px rgba(0, 0, 0, .5);
}

.modal-header {
 min-height: 16.42857143px;
 padding: 15px;
 border-bottom: 1px solid #e5e5e5;
}
.modal-header .close {
 margin-top: -2px;
}
.modal-title {
 margin: 0;
 line-height: 1.42857143;
}
.modal-body {
 position: relative;
 padding: 15px;
}
.modal-footer {
 padding: 15px;
 text-align: right;
 border-top: 1px solid #e5e5e5;
}
.modal-footer .btn + .btn {
 margin-bottom: 0;
 margin-left: 5px;
}
.modal-footer .btn-group .btn + .btn {
 margin-left: -1px;
}
.modal-footer .btn-block + .btn-block {
 margin-left: 0;
}

.modal {
 position: fixed;
 top: 0;
 right: 0;
 bottom: 0;
 left: 0;
 z-index: 1040;
 display: none;
 overflow: hidden;
 -webkit-overflow-scrolling: touch;
 outline: 0;
}

.modal-dialog {
 position: relative;
 width: auto;
 margin: 10px;
}

@media (min-width: 768px) {
 .modal-dialog {
 width: 600px;
 margin: 30px auto;
 }
 .modal-content {
 -webkit-box-shadow: 0 5px 15px rgba(0, 0, 0, .5);
   box-shadow: 0 5px 15px rgba(0, 0, 0, .5);
 }
 .modal-sm {
 width: 300px;
 }
}

.modal-backdrop {
 position: fixed;
 top: 0;
 right: 0;
 bottom: 0;
 left: 0;
 background-color: #000;
}

.modal-backdrop.fade {
 filter: alpha(opacity=0);
 opacity: 0;
}
.modal-backdrop.in {
 filter: alpha(opacity=50);
 opacity: .5;
}

<button type="button" data-toggle="modal" data-target="#mymodal" class="btn btn-primary">触发模态弹出窗</button>
<div class="modal" id="mymodal">
 <div class="modal-dialog">
  <div class="modal-content">
   <!-- 模态弹出窗内容 -->
  </div>
 </div>
</div>

<a data-toggle="modal" href="#mymodal" class="btn btn-primary" >触发模态弹出窗</a>
<div class="modal" id="mymodal" >
 <div class="modal-dialog" >
  <div class="modal-content" >
   <!-- 模态弹出窗内容 -->
  </div>
 </div>
</div>

.modal.fade .modal-dialog {
 -webkit-transition: -webkit-transform .3s ease-out;
  -o-transition:  -o-transform .3s ease-out;
   transition:   transform .3s ease-out;
 -webkit-transform: translate(0, -25%);
  -ms-transform: translate(0, -25%);
  -o-transform: translate(0, -25%);
   transform: translate(0, -25%);
}
.modal.in .modal-dialog {
 -webkit-transform: translate(0, 0);
  -ms-transform: translate(0, 0);
  -o-transform: translate(0, 0);
   transform: translate(0, 0);
}

<button type="button" class="btn btn-primary" id="mybtn">触发模态弹出窗</button>
<div class="modal" id="mymodal">
 <div class="modal-dialog">
  <div class="modal-content">
   <!-- 模态弹出窗内容 -->
  </div>
 </div>
</div>

$(function(){
 $("#mybtn").click(function(){
  $("#mymodal").modal();
 });
});