Abstract: The current design of subway facility scale is mainly based on the peak hour passenger flow with less attention paid to the impact of instantaneous passenger arrival rate, resulting in the slightly insufficient facility design capacity. In order to solve the mismatched problems between facility design capacity and passenger flow demands at subway stations, the method of calculating the peak passenger arrival rate is studied. According to the two states before and after the arrival of trains, the composition of passenger flow and its change rule are analyzed. Then, based on the passenger Poisson arrival process, a calculating formula for the peak passenger arrival rate is derived. Finally, taking Lujiabang Road Station of Shanghai urban rail transit as an example, the peak passenger arrival rate of different facilities is calculated, the calculated maximum value and the measured maximum value are compared and analyzed. Results show that the error between the two is less than 6%, thus the effectiveness of the proposed method is verified.