Step one: Open IIS, in your site to set up virtual directory property page tab, click on the “Application Settings (Application Settings)” under the “configuration (Configuration..)” Button, open the “application configuration (Application Configuration ) “window” App Mappings (App Mappings) “Tab page, click on the” Add (Add..) “button, the pop-up” Add / Edit Application Mapping suffix (Add / Edit Application Extension Mapping ) “window, in the” executable program (Executable) “the right of the text box, type C: \ WINNT \ Microsoft.NET \ Framework \ v1.1.4322 \ aspnet_isapi.dll (file path will be. net framework version of the different different for the sake of safety, you can in the “App Mappings (App Mappings)” tab under the list of double-mapping “. aspx”, in the pop-up window to select its “executable program (Executable)” text Copy the text box and then out), in the “name suffix (Extension)” text box you want to add the suffix of “. html”, then click OK to save all open windows to complete the property settings in IIS;
Step two: open you want to configure the site or virtual directory under the root directory of the web.config file, configuration section in <system.web> add the following configuration sections:
<httphandlers>
<add verb=”*”
path=”*.html”
type=”System.Web.UI.PageHandlerFactory” />
</httphandlers>
Save web.config file, Now we are set !!! 
