Abstract: The power system with high permeability of new energy is characterized by surplus energy and shortage of power,mainly because wind power（WP）and photovoltaic（PV）basically have no capacity benefit,therefore an effective way to solve this problem is using the complementary system consisting of pumped hydro storage（PHS）with WP and PV. A method for optimization of reasonable capacity benefit of the WP-PV-PHS complementary system,which takes the reasonable capacity benefit of the complementary system and the installed capacity of WP and PV as the decision variables of the optimization model,considers the new energy efficiency,power generation reliability and feasibility of national economy of the complementary system at the same time.The simulation results of a practical example show that the proposed algorithm can effectively solve the optimization of capacity benefit and installed capacity of the WP-PV-PHS complementary system.