方法一：

.aspx代碼

<form id="form1" method="post" runat="server">
   <font face="宋體">
    <asp:textbox id="textbox1"
     runat="server"></asp:textbox>
    <asp:button id="button1" runat="server"
     text="設 置"></asp:button>
    <asp:label id="label2" runat="server">動態設置textbox的樣式</asp:label>
    <asp:label id="label1" runat="server"></asp:label></font>
  </form>

.aspx.cs代碼

private void button1_click(object sender, system.eventargs e)
  {//設置樣式
   textbox1.style.add("width",textbox1.text.tostring());
   label1.text="寬度"+textbox1.style["width"].tostring();
  }

方法二：

.aspx代碼

<form id="form1" method="post" runat="server">
   <asp:label id="label1" runat="server">動態設置服務器控件的樣式</asp:label>
   <asp:button id="button1" runat="server"
    text="設　置"></asp:button>
   <asp:textbox id="textbox1" runat="server"></asp:textbox>
  </form>

.aspx.cs代碼

private void button1_click(object sender, system.eventargs e)
  {//設置樣式
   style style=new style();
   style.bordercolor=color.black;
   style.borderstyle=borderstyle.inset;
   style.borderwidth=new unit(1);
   textbox1.applystyle(style);
  }