如果你有这样一个下拉类的元素(例如):

<ul class="list-unstyled list-inline">
    <li class="dropdown">
        <a data-toggle="dropdown" href="#"><i class="fa fa-bars"></i> Dropdown 1</a>
        <ul class="dropdown-menu">
            <li><a href="">Item 1</a></li>
            <li><a href="">Item 2</a></li>
            <li><a href="">Item 3</a></li>
            <li><a href="">Item 4</a></li>
            <li><a href="">Item 5</a></li>
        </ul>
    </li>
    <li class="dropdown">
        <a data-toggle="dropdown" href="#"><i class="fa fa-user"></i> Dropdown 2</a>
        <ul class="dropdown-menu">
            <li><a href="">Item A</a></li>
            <li><a href="">Item B</a></li>
            <li><a href="">Item C</a></li>
            <li><a href="">Item D</a></li>
            <li><a href="">Item E</a></li>
        </ul>
    </li>
</ul>

然后你可以让下拉菜单自动下拉悬停，而不是必须点击它的标题，通过使用这段jQuery代码:

<script>
    $('.dropdown').hover(
        function() {
            $(this).find('.dropdown-menu').stop(true, true).delay(200).fadeIn();
        },
        function() {
            $(this).find('.dropdown-menu').stop(true, true).delay(200).fadeOut();
        }
    );

    $('.dropdown-menu').hover(
        function() {
            $(this).stop(true, true);
        },
        function() {
            $(this).stop(true, true).delay(200).fadeOut();
        }
    );
</script>

这是一个演示

这个答案依赖于@Michael的答案，我做了一些改变，并添加了一些补充，以使下拉菜单正常工作

这里是JSFiddle -> https://jsfiddle.net/PRkonsult/mn31qf0p/1/

底部的JavaScript部分是真正起作用的部分。

HTML

<!--http://getbootstrap.com/components/#navbar-->
<div class="body-wrap">
  <div class="container">
    <nav class="navbar navbar-inverse" role="navigation">
      <div class="container-fluid">
        <!-- Brand and toggle get grouped for better mobile display -->
        <div class="navbar-header">
          <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1">
            <span class="sr-only">Toggle navigation</span>
            <span class="icon-bar"></span>
            <span class="icon-bar"></span>
            <span class="icon-bar"></span>
          </button>
          <a class="navbar-brand" href="#">Brand</a>
        </div>

        <!-- Collect the nav links, forms, and other content for toggling -->
        <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
          <ul class="nav navbar-nav">
            <li class="active"><a href="#">Link</a></li>
            <li><a href="#">Link</a></li>
            <li class="dropdown">
              <a href="#" class="dropdown-toggle" data-toggle="dropdown">Dropdown <b class="caret"></b></a>
              <ul class="dropdown-menu">
                <li><a href="#">Action</a></li>
                <li><a href="#">Another action</a></li>
                <li><a href="#">Something else here</a></li>
                <li class="divider"></li>
                <li><a href="#">Separated link</a></li>
                <li class="divider"></li>
                <li><a href="#">One more separated link</a></li>
              </ul>
            </li>
          </ul>

          <ul class="nav navbar-nav navbar-right">
            <li><a href="#">Link</a></li>
            <li class="dropdown">
              <a href="#" class="dropdown-toggle" data-toggle="dropdown">Dropdown <b class="caret"></b></a>
              <ul class="dropdown-menu">
                <li><a href="#">Action</a></li>
                <li><a href="#">Another action</a></li>
                <li><a href="#">Something else here</a></li>
                <li class="divider"></li>
                <li><a href="#">Separated link</a></li>
              </ul>
            </li>
          </ul>
        </div>
        <!-- /.navbar-collapse -->
      </div>
      <!-- /.container-fluid -->
    </nav>
  </div>
</div>

CSS

/* Bootstrap dropdown hover menu */

body {
  font-family: 'PT Sans', sans-serif;
  font-size: 13px;
  font-weight: 400;
  color: #4f5d6e;
  position: relative;
  background: rgb(26, 49, 95);
  background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, rgba(26, 49, 95, 1)), color-stop(10%, rgba(26, 49, 95, 1)), color-stop(24%, rgba(29, 108, 141, 1)), color-stop(37%, rgba(41, 136, 151, 1)), color-stop(77%, rgba(39, 45, 100, 1)), color-stop(90%, rgba(26, 49, 95, 1)), color-stop(100%, rgba(26, 49, 95, 1)));
  filter: progid: DXImageTransform.Microsoft.gradient(startColorstr='#1a315f', endColorstr='#1a315f', GradientType=0);
}

.body-wrap {
  min-height: 700px;
}

.body-wrap {
  position: relative;
  z-index: 0;
}

.body-wrap: before,
.body-wrap: after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  z-index: -1;
  height: 260px;
  background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, rgba(26, 49, 95, 1)), color-stop(100%, rgba(26, 49, 95, 0)));
  background: linear-gradient(to bottom, rgba(26, 49, 95, 1) 0%, rgba(26, 49, 95, 0) 100%);
  filter: progid: DXImageTransform.Microsoft.gradient(startColorstr='#1a315f', endColorstr='#001a315f', GradientType=0);
}

.body-wrap:after {
  top: auto;
  bottom: 0;
  background: linear-gradient(to bottom, rgba(26, 49, 95, 0) 0%, rgba(26, 49, 95, 1) 100%);
  filter: progid: DXImageTransform.Microsoft.gradient(startColorstr='#001a315f', endColorstr='#1a315f', GradientType=0);
}

nav {
  margin-top: 60px;
  box-shadow: 5px 4px 5px #000;
}

JavaScript代码的重要部分:

$('ul.nav li.dropdown').hover(function() {
  $(this).find('.dropdown-menu').stop(true, true).delay(200).fadeIn(500);
}, function() {
  $(this).find('.dropdown-menu').stop(true, true).delay(200).fadeOut(500);
});

这样就把上面的隐藏起来了

.navbar .dropdown-menu:before {
   display:none;
}
.navbar .dropdown-menu:after {
   display:none;
}

这适用于WordPress Bootstrap:

.navbar .nav > li > .dropdown-menu:after,
.navbar .nav > li > .dropdown-menu:before {
    content: none;
}

还添加了margin-top:0来重置.dropdown-menu的引导css边距，这样当用户缓慢地从下拉菜单悬停到菜单列表时，菜单列表不会消失。

ul.nav li.dropdown:hover > ul.dropdown-menu {
    display: block;    
}

.nav .dropdown-menu {
    margin-top: 0;
}

在我看来，最好的办法是这样的:

;(function($, window, undefined) {
    // Outside the scope of the jQuery plugin to
    // keep track of all dropdowns
    var $allDropdowns = $();

    // If instantlyCloseOthers is true, then it will instantly
    // shut other nav items when a new one is hovered over
    $.fn.dropdownHover = function(options) {

        // The element we really care about
        // is the dropdown-toggle's parent
        $allDropdowns = $allDropdowns.add(this.parent());

        return this.each(function() {
            var $this = $(this),
                $parent = $this.parent(),
                defaults = {
                    delay: 500,
                    instantlyCloseOthers: true
                },
                data = {
                    delay: $(this).data('delay'),
                    instantlyCloseOthers: $(this).data('close-others')
                },
                settings = $.extend(true, {}, defaults, options, data),
                timeout;

            $parent.hover(function(event) {

                // So a neighbor can't open the dropdown
                if(!$parent.hasClass('open') && !$this.is(event.target)) {
                    return true;
                }

                if(settings.instantlyCloseOthers === true)
                    $allDropdowns.removeClass('open');

                window.clearTimeout(timeout);
                $parent.addClass('open');
            }, function() {
                timeout = window.setTimeout(function() {
                    $parent.removeClass('open');
                }, settings.delay);
            });

            // This helps with button groups!
            $this.hover(function() {
                if(settings.instantlyCloseOthers === true)
                    $allDropdowns.removeClass('open');

                window.clearTimeout(timeout);
                $parent.addClass('open');
            });

            // Handle submenus
            $parent.find('.dropdown-submenu').each(function(){
                var $this = $(this);
                var subTimeout;
                $this.hover(function() {
                    window.clearTimeout(subTimeout);
                    $this.children('.dropdown-menu').show();

                    // Always close submenu siblings instantly
                    $this.siblings().children('.dropdown-menu').hide();
                }, function() {
                    var $submenu = $this.children('.dropdown-menu');
                    subTimeout = window.setTimeout(function() {
                        $submenu.hide();
                    }, settings.delay);
                });
            });
        });
    };

    $(document).ready(function() {
        // apply dropdownHover to all elements with the data-hover="dropdown" attribute
        $('[data-hover="dropdown"]').dropdownHover();
    });
})(jQuery, this);

样本的标记:

<li class="dropdown">
    <a href="#" class="dropdown-toggle" data-toggle="dropdown" data-hover="dropdown" data-delay="1000" data-close-others="false">
        Account <b class="caret"></b>
    </a>
    <ul class="dropdown-menu">
        <li><a tabindex="-1" href="#">My Account</a></li>
        <li class="divider"></li>
        <li><a tabindex="-1" href="#">Change Email</a></li>
        <li><a tabindex="-1" href="#">Change Password</a></li>
        <li class="divider"></li>
        <li><a tabindex="-1" href="#">Logout</a></li>
    </ul>
</li>