最简单的办法，
使用一个块级元素包裹后，设置此块级元素为 text-center
<!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=1.0">
<title>bootstrap 101</title>
<link rel="stylesheet" href="https://www.52dixiaowo.com/tools/npm/bootstrap@3.4.1/dist/css/bootstrap.min.css">
<script src="https://www.52dixiaowo.com/tools/npm/jquery@1.12.4/dist/jquery.min.js"></script>
<script src="https://www.52dixiaowo.com/tools/npm/bootstrap@3.4.1/dist/js/bootstrap.min.js"></script>
</head>
<body>
<div class="col-xs-6 text-center bg-danger">
<button class="btn btn-default">按钮</button>
</div>
</body>
</html>本篇完，还有疑问？留下评论吧