Under the background of China's aggressive plans toward electricity market construction， the theory of optimal market structure is discussed. By analyzing the support mechanism（supporting policies） of electricity market construction and the factors considered in market risk avoidance mechanism， the market equilibrium analysis model of an interconnected network electricity market system mode is built， and the trading coordination mechanism and congestion management mechanism among trading platforms of interconnected power network are proposed with the astringency verification of market equilibrium model given. Finally， the influence of coal-electricity industry chain on the electricity market system mode is analyzed.