The paper proposed a method that endogenous two-sided network effects were proved in transaction services that the value of services to suppliers (buyers)increases with increasing number of buyers (suppliers) while decreases with increasing number of suppliers (buyers). Network led to the development pace of people’s lives; promote the development of online shopping and the rise of third-party payment platform. For more benefits, the platform owner must aim at transaction services of staple commodities with high price elasticity and large quantities of market supply and demand, while reducing the marginal usage costs of buyers and suppliers with effective measures.