A motor rotor system including: an axis of rotation, a rotor iron core mounted on the axis of rotation, a permanent magnet, a magnetic ring bracket, and a magnetic ring. The permanent magnet, the magnetic ring bracket, and the magnetic ring are mounted on the rotor iron core. The magnetic ring is sheathed on the magnetic ring bracket. The magnetic ring bracket is located at one end of the rotor iron core and connected with an end face of the rotor iron core. The motor rotor system has excellent batch-to-batch consistency, simple structure, and convenient installation. It is suitable for large batch production and can be controlled using sine-wave driving control methods with a position sensor.