Aiming at the problem that it is difficult to detect the rotor position of fault-tolerant permanent magnet rim drive motor (FTPM-RDM) at low speed, a rotor position estimation method based on generalized second-order integrator (SOGI) high-frequency voltage injection was proposed, that is, when FTPM-RDM operates at low speed, the high-frequency voltage signal was injected into the estimated synchronous rotating coordinate system to detect the six phase current containing rotor position information, and the rotor position information of the motor was extracted through the generalized second-order integrator. Compared with the traditional low-pass filter high-frequency voltage injection method, the proposed method can accurately estimate the rotor position information of the motor in the case of step change of torque and speed, open circuit fault of motor winding with the characteristics of good dynamic performance and small rotor position estimation error. Both simulation and experiment results verify the effectiveness of the proposed rotor position estimation algorithm.