Abstract: With the requirements of emergency unlocking function from CZJS/T 0022—2015 Urban Rail Transit Vehicle and Signaling System Interface Technology Requirement (Template) (Trial Version), three kinds of currently existing emergency unlocking device structures for metro trains are listed. Targeting metro door unlocking device for different structures, reasonable safety interlocking loop for metro vehicle door is designed. By analyzing the three schemes from various angles, the optimal scheme is obtained, and the running performance of metro trains and the safety of passengers are guaranteed, and the operating efficiency is improved.