Internet forum is the place where online mass incidents usually happen, and is very important in information diffusion and opinion spreading. We empirically analyze the interacting behavior of internet forum users, construct the virtual community network based on implicit interaction behavior. Through inspecting the statistical properties, we find that this virtual community network is directional, asymmetric and disassortative scale free network, and it has hierarchy and community structure.Moreover, user page view is positively correlated with his in-degree, so both can describe the influence power and popularity. From quantitative view, the results show that the effects of influential user with 'contribute-driven' property on information spreading can not be ignored; the success of internet forum needs to increase the activity of the most inert users; if user wants to be authoritative in virtual community networks, he needs to propose interesting message or has a personal brand.