With the development of internet technology and e-commerce，the effect of network externality on the sales of products becomes more and more important． Against this background，we explore the effect of network externality on pricing strategy． In this paper，we separate network externality into self-network externality and interactive network externality． We study on the impacts of different kinds of network externalities on the optimal market prices，market shares and profits． The main conclusions can be drawn as follows． Firstly，if only self-network externality exists，it has no effect on the optimal prices，while a significant influence on market shares and profits of different products． Secondly，if self and interactive network externality co-exist，the prices，market shares and profits of different products are all influenced by network externality．