The energy feedback system can be used to recycle the subway braking power,can greatly save energy.But in the experiment process of the energy feedback system,the subway starting and braking environment is lacked.This paper designs a renewable energy feedback experimental system consisting of two back to back inverters,and S1 simulates subway frequent starting and braking,S2 detects unblock or blocked conditions,automatically enter the feedback or standby state.The test results show that the test system quickly unlocks during simulation of the braking process of the subway,stabilizes the DC voltage at the same time,and quickly locks into the standby state during the simulation of the subway start-up process,providing experimental support for the on-site operation of the subway energy feeding system.