我使用了SCSS和全响应模态:

.modal-dialog.large {
    @media (min-width: $screen-sm-min) { width:500px; }
    @media (min-width: $screen-md-min) { width:700px; }
    @media (min-width: $screen-lg-min) { width:850px; }
} 

在css文件中添加以下内容

.popover{
         width:auto !important; 
         max-width:445px !important; 
         min-width:200px !important;
       }

更新:

在引导3中，你需要改变模式对话框。 所以在这种情况下，你可以在modal-dialog所在的位置添加类modal-admin。

原始答案(Bootstrap < 3)

是否有特定的原因，你试图改变它与JS/jQuery?

只需CSS就可以轻松完成，这意味着您不必在文档中进行样式化。 在您自己的自定义CSS文件中，您添加:

body .modal {
    /* new custom width */
    width: 560px;
    /* must be half of the width, minus scrollbar on the left (30px) */
    margin-left: -280px;
}

在你的情况下:

body .modal-admin {
    /* new custom width */
    width: 750px;
    /* must be half of the width, minus scrollbar on the left (30px) */
    margin-left: -375px;
}

我把body放在选择器之前的原因是，它的优先级比默认值更高。通过这种方式，您可以将其添加到自定义CSS文件中，并且无需担心更新Bootstrap。

尝试以下内容(参见jsfiddle示例:http://jsfiddle.net/periklis/hEThw/1/)

<a class="btn" onclick = "$('#myModal').modal('show');$('#myModal').css('width', '100px').css('margin-left','auto').css('margin-right','auto');" ref="#myModal" >Launch Modal</a>
<div class="modal" id="myModal" style = "display:none">
  <div class="modal-header">
    <a class="close" data-dismiss="modal">×</a>
    <h3>Modal header</h3>
  </div>
  <div class="modal-body">
    <p>One fine body…</p>
  </div>
  <div class="modal-footer">
    <a href="#" class="btn">Close</a>
    <a href="#" class="btn btn-primary">Save changes</a>
  </div>
</div>​

在Bootstrap 3中，你所需要的就是这个

<style>
    .modal .modal-dialog { width: 80%; }
</style>

上面的大部分答案对我来说都没用!!

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.5/js/bootstrap.min.js"></script> <link href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.5/css/bootstrap.min.css" rel="stylesheet" /> <style> #myModal1 .modal-dialog { width: 80%; } #myModal2 .modal-dialog { width: 50%; } </style> <button type="button" class="btn btn-primary btn-lg" data-toggle="modal" data-target="#myModal1"> 80% </button> <button type="button" class="btn btn-primary btn-lg" data-toggle="modal" data-target="#myModal2"> 50% </button> <center> <!-- Modal --> <div class="modal fade" id="myModal1" tabindex="-1" role="dialog" aria-labelledby="myModalLabel"> <div class="modal-dialog" role="document"> <div class="modal-content"> <div class="modal-header"> <button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">&times;</span> </button> <h4 class="modal-title" id="myModalLabel">Modal title</h4> </div> <div class="modal-body"> custom width : 80% </div> <div class="modal-footer"> <button type="button" class="btn btn-default" data-dismiss="modal">Close</button> <button type="button" class="btn btn-primary">Save changes</button> </div> </div> </div> </div> <!-- Modal --> <div class="modal fade" id="myModal2" tabindex="-1" role="dialog" aria-labelledby="myModalLabel"> <div class="modal-dialog" role="document"> <div class="modal-content"> <div class="modal-header"> <button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">&times;</span> </button> <h4 class="modal-title" id="myModalLabel">Modal title</h4> </div> <div class="modal-body"> custom width : 50% </div> <div class="modal-footer"> <button type="button" class="btn btn-default" data-dismiss="modal">Close</button> <button type="button" class="btn btn-primary">Save changes</button> </div> </div> </div> </div> </center>

达到预期效果使用，

.modal-dialog {
    width: 41% !important;
}