The invention discloses a permanent magnet rotating speed difference clutch and a self-adaption nonsingular terminal slip form rotating speed control method thereof. The method is characterized in that (1) an outer rotor of a permanent magnet rotating speed difference clutch is connected with an engine, and an inner rotor is connected with a steering pump, and then a permanent magnet rotating speed difference clutch type electronically controlled hydraulic power steering system can be formed; (2) a permanent magnet rotating speed difference clutch mathematic model can be established, and comprises a voltage equation, an electromagnetic torque equation, and a motion equation; (3)according to the mathematic mode, the self-adaption nonsingular terminal slip form surface can be designed by adopting the self-adaption nonsingular terminal slip form control method, and the control law can be deduced, and the self-adaption law of the parameter uncertain factors can be designed by adopting the Lyapunov stability theory, and the stability of the control system can be guaranteed. By adopting the self-adaption nonsingular terminal slip form control method, the problems of the system parameter perturbation and the external interference uncertainty can be overcome, the jitter can be reduced, the strong robustness can be provided, the accurate control over the permanent magnet rotating speed difference clutch output rotating speed can be realized, and the tracking error can be reduced to zero quickly.