The post-assembly magnetization technology can reduce the manufacturing cost, improve production efficiency, and ensure the product quality and performance of permanent magnet motors. Taking a 16-pole disk motor as a prototype, this paper introduces the design process of the post-assembly magnetization system of the rotor of a disk coreless permanent magnet motor based on the Halbach array. Racetrack-like magnetizing windings with longer outer ends and shorter inner ends are used to magnetize the motor. The corresponding two-dimensional and three-dimensional finite element simulation models are established. The influence of the geometric dimensions and turns of the magnetizing coil on the magnetizing field is studied. The magnetizing coil stress and temperature during magnetization are simulated and analyzed, and then the corresponding magnetization scheme is designed. The simulation results show that the designed post-assembly magnetization system successfully magnetizes the rotor of a disk coreless permanent magnet motor.