Aiming at the problem of high consumption of rare earth permanent magnet materials in traditional rare earth permanent magnet motor, this paper proposes a rare earth permanent magnet synchronous motor with alternating pole and local Halbach structure composed of NdFeB and ferrite hybrid permanent magnets, and analyzes the structural characteristics of the hybrid permanent magnet motor. The electromagnetic performance of the motor and the traditional one-shaped Nd-Fe-B rare earth permanent magnet motor is compared and analyzed, and the local demagnetization finite element model of the motor is established according to the demagnetization characteristics. The multi-operating conditions of the motor are simulated by magnetic circuit coupling co-simulation. Aiming at the performance loss of local demagnetization of the motor under high-speed field weakening and variable load operating conditions, the anti-demagnetization optimization design scheme of the motor is given to improve the working point of the permanent magnet and reduce the demagnetization rate. The simulation results verify the rationality of the proposed motor structure, and the anti-demagnetization performance of the motor is improved by 10.3% compared with that before optimization.