With the development of the electric power system reform and the electricity market,a completely-open electricity market will be gradually established corresponding to the opening of the demand side.In this paper,by introducing the cost matrix of the generator and the expected pay vector of the purchaser,a bilateral trading mechanism involving a number of market participators is established based on the Nash equilibrium theory,and the genetic algorithm with strong global search ability is employed to solve the model.Simulated results show that the proposed model is practical and feasible,and that it helps to find the Nash equilibrium strategy combination with the smallest total cost,thus maximizing the benefit of each market participator.It is also indicated that the proposed strategy well reflects the effect of bidding strategies of the generator on the electricity market.