您可以使用多个ID为 myTabContent 。

You have more than one element with id myTabContent.

HTML ID在整个页面上应该是唯一的。

HTML ids should be unique across the page.

只需删除这些ID或使用类即可（在此处工作演示）。

Simply remove those ids or use classes instead (working demo here).

$("ul.nav-tabs a").click(function (e) {
  e.preventDefault();
  $(this).tab('show');
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet"/>


<div class="tabbable boxed parentTabs">
    <ul class="nav nav-tabs">
        <li class="active"><a href="#set1">Tab 1</a>
        </li>
        <li><a href="#set2">Tab 2</a>
        </li>
    </ul>
    <div class="tab-content">
        <div class="tab-pane fade active in" id="set1">
            <div class="tabbable">
                <ul class="nav nav-tabs">
                    <li class="active"><a href="#sub11">Tab 1.1</a>
                    </li>
                    <li><a href="#sub12">Tab 1.2</a>
                    </li>
                </ul>
                <div class="tab-content">
                    <div class="tab-pane fade active in" id="sub11">
                        <p>Tab 1.1</p>
                    </div>
                    <div class="tab-pane fade" id="sub12">
                        <p>Tab 1.2</p>
                    </div>
                </div>
            </div>
        </div>
        <div class="tab-pane fade" id="set2">
            <div class="tabbable">
                <ul class="nav nav-tabs">
                    <li class="active"><a href="#sub21">Tab 2.1</a>
                    </li>
                    <li><a href="#sub22">Tab 2.2</a>
                    </li>
                </ul>
                <div class="tab-content">
                    <div class="tab-pane fade active in" id="sub21">
                        <p>Tab 2.1</p>
                    </div>
                    <div class="tab-pane fade" id="sub22">
                        <p>Tab 2.2</p>
                    </div>
                </div>
            </div>
        </div>
    </div>
</div>