Abstract: The three-phase asynchronous motor is widely used in high-risk industries such as coal mines. Its operation stability and fault response characteristics are directly related to the system safety. In this paper, the system modeling and simulation research are carried out around the problem that the back electromotive force generated by the motor under the condition of instantaneous power failure may cause interference to the leakage blocking device. Based on the Simulink platform, a three-phase asynchronous motor power supply model with frequency converter is constructed. After the normal operation of the motor, the power is cut off at a specific time. The dynamic changes of stator current, rotor current, electromagnetic torque and back electromotive force are obtained by time domain analysis. The simulation results show that the motor still has a strong back electromotive force due to the inertia of the rotor at the moment of power failure, the maximum amplitude is close to 70 V, and it has obvious oscillation characteristics. The back electromotive force and the current and torque caused by it gradually decay to a negligible level within about 4.5 s. The voltage fluctuation under different ground insulation resistance conditions is further compared, and it is verified that the interference to the additional DC detection system is basically eliminated after 5 s. Based on the above results, a reasonable back-EMF avoidance strategy is proposed, which provides a basis for the safety response timing design of the leakage blocking device.