原文:
http://msdn.microsoft.com/en-us/library/system.windows.forms.webbrowser.goback.aspx

Code
// Navigates webBrowser1 to the previous page in the history.
private void backButton_Click(object sender, EventArgs e)
{
webBrowser1.GoBack();
}
// Disables the Back button at the beginning of the navigation history.
private void webBrowser1_CanGoBackChanged(object sender, EventArgs e)
{
backButton.Enabled = webBrowser1.CanGoBack;
}