Subway energy feedback system can put the subway brake energy back to the power grid,to save energy and stabilize DC voltage.The design of the charging circuit is related to not only the secure operation of the energy feedback device,but also the impact on the power grid when the device is connected to the power grid.After analyzing the working principle of subway energy feedback system,AC charging and DC charging,the two design schemes are given with their charging process.Through building 1.2 MW back-to-back test platform system,the charging experiment and the grid connection experiment have been conducted.The results show that the DC charging scheme is the ideal charging scheme,not only because it meets the cut-in requirements of the subway energy feedback system,but also because its operation process is simple and reliable.