According to industrial organization theory development, the fundamental influence factors to the market efficiency are the market structure (Harvard school), technology (Chicago school), and transaction costs (new industrial organization theory) and so on.E-Commerce taken as the new productivity (Li Qi, 1999), its market efficiency is restricted or promoted by these influence too.In the E-Commerce transaction market structure, the monopolistic competition and perfect competition market structure are compatible with each other The enterprise carried on the technical innovation function is interconvertible in the two kinds of market structure.It reduced the transaction frequency, strengthens the both transaction sides information communication, cut down the asymmetrical information and so on.So compared to the traditional transaction the E-Commerce market transaction costs reduce greatly.