在div .item中您有.row,並且您有4個.col-md-3 div您刪除了其他3並留下一個並給它一個類.col-md-12。試試這個 這是你想要的嗎? http://jsfiddle.net/bGwXd/1/
<div id="myCarousel" class="carousel slide">
<div class="carousel-inner">
<div class="item active">
<div class="row">
<div class="col-md-12">
<div class="thumbnail">
<img src="http://placehold.it/300x200/" alt="Slide12">
<div class="caption">
<h3>Product label</h3>
<p>Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor</p>
<p><a href="#" class="btn btn-primary" role="button">12,99 €</a> <a href="#" class="btn btn-default" role="button">Wishlist</a></p>
</div>
</div>
</div>
</div>
</div>
<div class="item">
<div class="row">
<div class="col-md-3">
<div class="thumbnail">
<img src="http://placehold.it/300x200/" alt="Slide21">
<div class="caption">
<h3>Product label</h3>
<p>Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor</p>
<p><a href="#" class="btn btn-primary" role="button">12,99 €</a> <a href="#" class="btn btn-default" role="button">Wishlist</a></p>
</div>
</div>
</div>
<div class="col-md-3">
<div class="thumbnail">
<img src="http://placehold.it/300x200/" alt="Slide22">
<div class="caption">
<h3>Product label</h3>
<p>Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor</p>
<p><a href="#" class="btn btn-primary" role="button">12,99 €</a> <a href="#" class="btn btn-default" role="button">Wishlist</a></p>
</div>
</div>
</div>
<div class="col-md-3">
<div class="thumbnail">
<img src="http://placehold.it/300x200/" alt="Slide23">
<div class="caption">
<h3>Product label</h3>
<p>Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor</p>
<p><a href="#" class="btn btn-primary" role="button">12,99 €</a> <a href="#" class="btn btn-default" role="button">Wishlist</a></p>
</div>
</div>
</div>
<div class="col-md-3">
<div class="thumbnail">
<img src="http://placehold.it/300x200/" alt="Slide24">
<div class="caption">
<h3>Product label</h3>
<p>Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor</p>
<p><a href="#" class="btn btn-primary" role="button">12,99 €</a> <a href="#" class="btn btn-default" role="button">Wishlist</a></p>
</div>
</div>
</div>
</div>
</div>
<div class="item">
<div class="row">
<div class="col-md-3">
<div class="thumbnail">
<img src="http://placehold.it/300x200/" alt="Slide31">
<div class="caption">
<h3>Product label</h3>
<p>Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor</p>
<p><a href="#" class="btn btn-primary" role="button">12,99 €</a> <a href="#" class="btn btn-default" role="button">Wishlist</a></p>
</div>
</div>
</div>
<div class="col-md-3">
<div class="thumbnail">
<img src="http://placehold.it/300x200/" alt="Slide32">
<div class="caption">
<h3>Product label</h3>
<p>Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor</p>
<p><a href="#" class="btn btn-primary" role="button">12,99 €</a> <a href="#" class="btn btn-default" role="button">Wishlist</a></p>
</div>
</div>
</div>
<div class="col-md-3">
<div class="thumbnail">
<img src="http://placehold.it/300x200/" alt="Slide33">
<div class="caption">
<h3>Product label</h3>
<p>Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor</p>
<p><a href="#" class="btn btn-primary" role="button">12,99 €</a> <a href="#" class="btn btn-default" role="button">Wishlist</a></p>
</div>
</div>
</div>
<div class="col-md-3">
<div class="thumbnail">
<img src="http://placehold.it/300x200/" alt="Slide34">
<div class="caption">
<h3>Product label</h3>
<p>Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor</p>
<p><a href="#" class="btn btn-primary" role="button">12,99 €</a> <a href="#" class="btn btn-default" role="button">Wishlist</a></p>
</div>
</div>
</div>
</div>
</div>
</div>
<a class="left carousel-control" href="#myCarousel" data-slide="prev"><i class="fa fa-chevron-left fa-2x"></i></a>
<a class="right carousel-control" href="#myCarousel" data-slide="next"><i class="fa fa-chevron-right fa-2x"></i></a>
<ol class="carousel-indicators">
<li data-target="#myCarousel" data-slide-to="0" class="active"></li>
<li data-target="#myCarousel" data-slide-to="1"></li>
<li data-target="#myCarousel" data-slide-to="2"></li>
</ol>
</div><!-- End Carousel -->
請創建您的問題的小提琴/ bootply併爲我們提供了在這裏你的問題是一些代碼。 – Sebsemillia
我更新它,這裏是我的小提琴:http://jsfiddle.net/bGwXd/ – Zwen2012