方法一: <HEAD><title>WebForm1</title><LINK rel="stylesheet" type="text/css" href="" id="mycss"></HEAD> private void Button1_Click(object sender, System.EventArgs e) {Page.RegisterStartupScript("css",@"<script>mycss.styleSheet.addImport('stylesheet1.css')</script>"); } 方法二:--- 戏子的方法..嘻..抄来的... <HEAD> <title>WebForm1</title> <asp:placeholder id="myplaceholder" runat="server"></asp:placeholder> </HEAD> private void Button2_Click(object sender, System.EventArgs e) { System.Web.UI.Control a = Page.FindControl("myplaceholder"); System.Web.UI.HtmlControls.HtmlGenericControl objLink = new HtmlGenericControl("LINK"); objLink.Attributes.Add("rel","stylesheet"); objLink.Attributes.Add("type","text/css"); objLink.Attributes.Add("href","StyleSheet1.css"); objLink=objLink; a.Controls.Add(objLink); } [注] asp:placeholder 这是控件是主要是起"占位符的做用" 转载于:https://www.cnblogs.com/mmmhhhlll/archive/2004/12/02/72136.html