Thanks a lot.
Noseratio gives the correct answer. But his words is tagged as comments and unable to be rated .
Also , as the complement , For X64 version : the registry key is : HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Internet Explorer\MAIN\FeatureControl\FEATURE_BROWSER_EMULATION. I almost give it up because I am routed to : HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\MAIN\FeatureControl\FEATURE_BROWSER_EMULATION
Plesae refer to the link for details.
http://www.cnblogs.com/philzhou/archive/2012/12/02/2798204.html.