下拉框重写

$(function () {
    $(".select-default").selectOpen();
});
$.fn.selectOpen = function () {
    var singleSelect = function (parentObj) {
        parentObj.addClass("single-select"); //添加样式
        parentObj.children().hide(); //隐藏内容
        var sltWidth = parentObj.attr("width"); //定义宽度
        var sltHeight = parentObj.attr("height"); //定义高度
        var divObj = $(‘<div class="boxwrap focus"></div>‘).prependTo(parentObj); //前插入一个DIV
        divObj.css("width", sltWidth); //写入宽度
        //创建元素
        var titObj = $(‘<a class="select-tit" href="javascript:;"><span></span><i></i></a>‘).appendTo(divObj);
        var itemObj = $(‘<div class="select-items"><ul></ul></div>‘).appendTo(divObj);
        itemObj.find("ul").css("width", sltWidth);
        itemObj.find("ul").css("height", sltHeight);
        var selectObj = parentObj.find("select").eq(0); //取得select对象
        //遍历option选项
        selectObj.find("option").each(function (i) {
            var indexNum = selectObj.find("option").index(this); //当前索引
            var liObj = $(‘<li title="‘ + $(this).text() + ‘">‘ + $(this).text() + ‘</li>‘).appendTo(itemObj.find("ul")); //创建LI
            if ($(this).prop("selected") == true) {
                liObj.addClass("selected");
                titObj.find("span").text($(this).text()).attr("title", $(this).text());
            }
            //检查控件是否启用
            if ($(this).prop("disabled") == true) {
                liObj.css("cursor", "default");
                return;
            }
            //绑定事件
            liObj.click(function () {
                $(this).siblings().removeClass("selected");
                $(this).addClass("selected"); //添加选中样式
                selectObj.find("option").prop("selected", false);
                selectObj.find("option").eq(indexNum).prop("selected", true); //赋值给对应的option
                titObj.find("span").text($(this).text()).attr("title", $(this).text()); //赋值选中值
                itemObj.hide(); //隐藏下拉框
                selectObj.trigger("change"); //触发select的onchange事件

            });
        });

        //检查控件是否启用
        if (selectObj.prop("disabled") == true) {
            titObj.css("cursor", "default");
            return;
        }
        //绑定单击事件
        titObj.click(function (e) {
            e.stopPropagation();
            //表单验证提示信息点击之后消失
            $(this).parents(".pst-rela").find(".tips-text").hide();
            if (itemObj.is(":hidden")) {
                selectObj.trigger("click"); //触发select的click事件

                //隐藏其它的下位框菜单
                $(".single-select .select-items").hide();
                //位于其它无素的上面
                itemObj.css("z-index", "51");
                //显示下拉框
                itemObj.show();
                //加深边框颜色
                //divObj.addClass(‘focus‘);    

            } else {
                //位于其它无素的上面
                itemObj.css("z-index", "");
                selectObj.trigger("blur"); //触发select的onblure事件
                //隐藏下拉框
                itemObj.hide();
                //去除边框颜色
                //divObj.removeClass(‘focus‘);
            }
        });
        //绑定页面点击事件
        $(document).click(function (e) {
            selectObj.trigger("blur"); //触发select的onblure事件
            itemObj.hide(); //隐藏下拉框
            //divObj.removeClass(‘focus‘);//去除边框颜色
        });
    };
    return $(this).each(function () {
        singleSelect($(this));
    });
}
//下拉框重写结束

<div class="select-default">
    <select >
        <option value="">这样就可以啦</option>
    </select>
</div>

.single-select ol, ul
{
    list-style: none;
    padding: 0;
    margin: 0;
}
.single-select
{
    position: relative;
    display: inline-block;
    font-family: Microsoft YaHei;
    color: #666;
    font-size: 14px;
    text-align: left;
    vertical-align: middle;
    cursor: pointer;
}
.single-select .boxwrap
{
    display: inline-block;
    width: 161px;
    border: solid 1px #d6d6d6;
    vertical-align: middle;
}
.single-select .boxwrap.focus, .single-select .boxwrap.focus ul
{
    border: solid 1px #ed9334;
}
.single-select .select-tit
{
    position: relative;
    display: block;
    padding: 0 36px 0 5px;
    line-height: 26px;
    height: 26px;
    text-decoration: none;
    background: #fff;
    word-break: break-all;
    color: #666;
    overflow: hidden;
}
.single-select .select-tit span
{
    display: inline-block;
    height: 26px;
}
.single-select .select-tit i
{
    position: absolute;
    right: 0;
    top: 0;
    display: inline-block;
    width: 26px;
    height: 26px;
    background: url(../images/sprite.png) -134px -20px no-repeat;
}
.boxwrap.focus i{
    background-position:-134px -20px;
}
.single-select .select-items
{
    display: none;
    position: absolute;
    left: 0;
    top: 31px;
}
.select-up .select-items
{
    top:auto;
    bottom:31px;
}
.single-select .select-items ul
{
    position: relative;
    width: 161px;
    max-height: 130px;
    border: 1px solid #d6d6d6;
    background: #fff;
    overflow-y: auto;
    overflow-x: hidden;
}
.single-select .select-items ul li
{
    display: block;
    padding-left: 5px;
    line-height: 26px;
    height: 26px;
    overflow: hidden;
    cursor: pointer;
}
.single-select .select-items ul li:hover
{
    color:#ed9334;
}
.single-select .select-items ul li.selected
{
    background: #ed9334;
    color:#fff;
}
.single-select.disabled .boxwrap
{
    border: 1px solid #d6d6d6;
}
.single-select.disabled .select-tit
{
    color:#b3b3b3;
    cursor:default;
}
.single-select.disabled .select-items
{
    display:none !important;
}
/* 下拉框样式结束 */

CSS

完整压缩包下载地址：http://pan.baidu.com/s/1i3yI5Ul