Anyone can help me! I was implement OU in my network system and control by GPO. The problem is how can I enable file sharing on my normal user account? the sharing tab not appear after right click folder. What the best setting for users in OU especially for normal user? My setting for "member of" in user account is "domain users".

You are applying peer to peer networking concepts to client/server. In client/server users never setup shares. Admins do. Users just access resources they have been granted access to. They do not control that access, admins do.

Sorry, if I want to give sharing permission to user, how can I do? some time user need to sharing file among of them without request permission from admin.

That case never exists. If it does it was due to a lack of planning on the part of the network admin. You setup share points the users can place the files they want shared for everyone / limited amount of users. Otherwise you have to give users admin access to the server. Hope you like disasters and data loss. Users as server admins is the fastest way to trash the server I know. Far better than a virus. You should get a book on server administration so you have a clear understanding.