When building a new power system with the theme of new energy, the power grid is facing a huge challenge of a sharp increase in electrical traffic load represented by electric vehicles. To solve the above problem, a load balancing optimization model is proposed, one which integrates the aggregate electric vehicles after load balancing into the power grid in turn. Then, using a multi-agent consensus algorithm, the incremental cost of the generation unit and the incremental benefit of the aggregate electric vehicle are taken as the consistency variables, and an algorithm for the aggregate electric vehicle to participate in the economic dispatch of the power system is designed. The economic dispatch problem is solved by distributed optimization. Four typical simulation scenarios are established to verify the effectiveness of aggregate electric vehicles participating in distributed optimal dispatch of a power system step by step. The applicability of different communication topologies and power constraints and the ability of a distributed optimization algorithm to ''plug and play'' when aggregate electric vehicles participate in economic dispatch are also verified. Simulation results on IEEE 39-bus system verify the effectiveness of the strategy. This work is supported by the National Natural Science Foundation of China (No. 61340041 and No. 61374079).