<!DOCTYPE html> <html lang="zh"> <head> <meta charset="UTF-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <meta http-equiv="X-UA-Compatible" content="ie=edge" /> <title>Document</title> <style type="text/css"> .option_show { display: none; } .discount { width: 70px; } </style> </head> <body> <select class="select" name="oyhfd"> <option value="0" selected="selected">请选择</option> <option class="option" value="1">足球</option> <option class="option" value="2">篮球</option> <option class="option" value="3">乒乓球</option> <option class="option" value="4">网球</option> </select> <span style="display:none;" class="option_show"> <input type="text" class="discount" id="" name="" placeholder="其他球类"/> </span> </body> <script src="https://code.jquery.com/jquery-3.1.1.min.js"></script> <script> $(".select").on("change", function() { if($("option:selected", this).val() == 4) { $(".option_show").show(); } else { $(".discount").val(""); $(".option_show").hide(); } }); </script> </html>