Method  With the gradual advancement of the power market reform， the competition of generation side was more diversified and the selling side was gradually liberalized. Traditional planning methods of power grid might no longer be applicable in the power market. In this paper， the main causes of the inconsistency between power supply and power grid development under the new environment of power market were analyzed from the aspects of uncertainty of power supply development and power flow.

  Result  The cost-benefit method to Evaluate Economic Efficiency is applied. By calculating the net benefit of the system with or without the project， the benefit-cost ratio BCR of each project is finally obtained， which is used to optimize the power distribution and serve as an important basis for the decision-making of power grid projects.

  Conclusion  It is suggested that the coordination between generation and transmission in power market can be promoted by optimizing and improving the method of power grid planning and establishing an evaluation system of power grid economic efficiency.