The utility model relates to the technical field of plastic magnetic rotors, and discloses a plastic magnetic rotor for a precision motor, which comprises a supporting mechanism, a limiting mechanism and a rotor mechanism, the supporting mechanism is positioned on the surface of the rotor mechanism, and the limiting mechanism is positioned on the surface of the supporting mechanism. The supporting mechanism comprises a rotating sleeve, a connecting sleeve is clamped to the inner wall of the rotating sleeve, a sliding inner plate is slidably connected to the inner wall of the connecting sleeve, a supporting sleeve rod is fixedly connected to the surface of the connecting sleeve, a limiting shaft is in threaded connection with the inner wall of the supporting sleeve rod, and a sliding inner shaft is slidably connected to the inner wall of the supporting sleeve rod. And a limiting groove is formed in the surface of the sliding inner shaft. Through the design that the sliding inner shaft is used for sliding adjustment on the inner wall of the supporting sleeve rod and the rotating sleeve is used for supporting the rotor body, the purposes that the rotor is more stable during rotation and the rotor can be conveniently detached and replaced by rotating the connecting sleeve when the rotor is damaged are achieved, use is more convenient, and practicability is improved.