Aiming at the problem that the existing power vehicle cannot maintain constant power due to the change of pedaling rate in the test and training process, a new magnetoresistance generation device is proposed. Firstly, the magnetoresistance generation device is designed based on the principle of permanent magnet synchronous motor. The basic structural dimensions of the device are determined through the overall structure of the power car. Considering the maximum power required for the test, the electromagnetic load and select permanent magnets are determined. Then the stator and rotor structure size and winding connection form are designed, and the radial air gap parameter is specified. Finally, the system constant power control principle is analyzed. The system constant power control effect is simulated and experimented by fuzzy PID control and iterative learning control ( ILC ). The results show that the power error of the new magnetoresistive power vehicle can be controlled within ±5 W when the pedaling speed varies in the range of 60(±10) r/ min, which is acceptable. The power vehicle with the new magnetoresistance generation device improves the effect of constant power control and verifies its advancement in maintaining constant power.