1.html页面（如果效果出不来，注意修改单引号）
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1, user-scalable=no">
<title>bootstrap</title>
<link href="css/bootstrap.css" rel="stylesheet">
<!--[if lt IE 9]>
<script src="js/html5shiv.min.js"></script>
<script src="js/respond.min.js"></script>
<![endif]-->
</head>
<body>
<button type="button" id="modalBtn" class="btn btn-primary">点击弹modal</button>
<div class="modal fade" id="myModal">
<div class="modal-dialog">
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">×</span></button>
<h4 class="modal-title">Modal 标题</h4>
</div>
<div class="modal-body">
<p>内容…</p>
</div>
<div class="modal-footer">
<button type="button" class="btn btn-default" data-dismiss="modal">关闭</button>
<button type="button" class="btn btn-primary">确定</button>
</div>
</div><!-- /.modal-content -->
</div><!-- /.modal-dialog -->
</div><!-- /.modal -->
<br><br><br><br><br><br><br><br><br><br><br><br>
<script src="js/jquery-1.11.3.js"></script>
<script src="js/bootstrap.js"></script>
<script>
var $m_btn = $(‘#modalBtn‘);
var $modal = $(‘#myModal‘);
$m_btn.on(‘click‘, function(){
$modal.modal({backdrop:‘static‘});
});
/*(function () {
var s = document.createElement("script");
s.onload = function () {
bootlint.showLintReportForCurrentDocument([]);
};
s.src = "js/bootlint.js";
document.body.appendChild(s)
})();*/
</script>
</body>
</html>
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1, user-scalable=no">
<title>bootstrap</title>
<link href="css/bootstrap.css" rel="stylesheet">
<!--[if lt IE 9]>
<script src="js/html5shiv.min.js"></script>
<script src="js/respond.min.js"></script>
<![endif]-->
</head>
<body>
<button type="button" id="modalBtn" class="btn btn-primary">点击弹modal</button>
<div class="modal fade" id="myModal">
<div class="modal-dialog">
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">×</span></button>
<h4 class="modal-title">Modal 标题</h4>
</div>
<div class="modal-body">
<p>内容…</p>
</div>
<div class="modal-footer">
<button type="button" class="btn btn-default" data-dismiss="modal">关闭</button>
<button type="button" class="btn btn-primary">确定</button>
</div>
</div><!-- /.modal-content -->
</div><!-- /.modal-dialog -->
</div><!-- /.modal -->
<br><br><br><br><br><br><br><br><br><br><br><br>
<script src="js/jquery-1.11.3.js"></script>
<script src="js/bootstrap.js"></script>
<script>
var $m_btn = $(‘#modalBtn‘);
var $modal = $(‘#myModal‘);
$m_btn.on(‘click‘, function(){
$modal.modal({backdrop:‘static‘});
});
/*(function () {
var s = document.createElement("script");
s.onload = function () {
bootlint.showLintReportForCurrentDocument([]);
};
s.src = "js/bootlint.js";
document.body.appendChild(s)
})();*/
</script>
</body>
</html>
2.修改bootstrap.js 源码
打开bootstrap.js ctrl+f 找到 modal对应代码
Modal.prototype.adjustDialog = function () {
var modalIsOverflowing = this.$element[0].scrollHeight > document.documentElement.clientHeight
this.$element.css({
paddingLeft: !this.bodyIsOverflowing && modalIsOverflowing ? this.scrollbarWidth : ‘‘,
paddingRight: this.bodyIsOverflowing && !modalIsOverflowing ? this.scrollbarWidth : ‘‘
})
// 添加下面三行代码，注意修改单引号！
var $modal_dialog = $(this.$element[0]).find(‘.modal-dialog‘);
var m_top = ( $(document).height() - $modal_dialog.height() )/2;
$modal_dialog.css({‘margin‘: m_top + ‘px auto‘});
}
这个样子就实现modal垂直居中了！
原文：http://www.cnblogs.com/liliyasuolong/p/5105521.html