After the factors influencing knowledge sharing were analyzed, it was supposed that virtual communities would be one of the most effective ways to knowledge-sharing. The implications of virtual communities and its organizational structure were described, and a framework of the model for knowledge sharing-oriented virtual communities was presented. The structures of three levees of the framework, including denotation layer, application one and storage one, and their factions were studied.  Several steps were given to realize virtual communities. This framework can give a reference to building virtual communities and sharing knowledge.