1. 添加CSS样式: Style style = new Style(); style.ForeColor = System.Drawing.Color.Navy; style.BackColor = System.Drawing.Color.LightGray; this.Header.StyleSheet.CreateStyleRule(style, null, "body"); 2. 链接外部的CSS样式表: HtmlLink link = new HtmlLink(); link.Attributes.Add("type", "text/css"); link.Attributes.Add("rel", "stylesheet"); link.Attributes.Add("href", "~/newstyle.css"); this.Header.Controls.Add(link); 方法3 aa.aspx.cs public string m_StyleSrc = string.Empty; //公共变量 ,样式文件路径 private void Page_Load(object sender, System.EventArgs e) { m_StyleSrc = "../xxx.css"; //页面加载时赋值 } } aa.aspx <LINK href="<%=m_StyleSrc%>" type="text/css" rel="stylesheet"> 方法4 下面这个方法没试过,不知是否能用 protected void Page_Onload(object sender, EventArgs e) { Page.StyleSheetTheme = "../css/infomore.css"; } 方法5 页面： <link href="" rel="stylesheet" type="text/css" id="css" runat="server"/> 后台 this.css.Href = "css文件路径";