Abstract: The Internet economy distinguishes itself from other economic forms，adding new characteristics to market competition: high fixed cost with low marginal cost，obvious network effects and lockin principles，rapid technological innovation and dynamic competition，etc. These changes are posing questions as to how the antimonopoly regulations originating from traditional industrial economy could contain the misuse of monopoly power in the context of internet economy. The friction between 360 and Tencent happened to be the right test stone. Through analyzing monopoly power misuse，explaining the uniqueness of internet economy，and inspecting the 360 versus Tencent issue，this article aims to answer the questions of how law enforcement departments should handle similar cases，and how antimonopoly law could prevent market power misuse on the macroeconomic level in the new situation.

Key words: net economy, network effects, 360 versus Tencent friction, abuse of dominant market position, antimonopoly law