A motor cooling system, a motor stator and a disc motor. The motor cooling system comprises an insulated cooling pipeline (2); the insulated cooling pipeline is mounted on a stator housing, the top surface of the insulated cooling pipeline is lower than or flush with the top surface of a stator iron core, and the bottom surface of the insulated cooling pipeline touches a coil of the motor stator for use in cooling the coil; the top surface of the stator iron core is configured to being arranged relative to a rotor, so that a magnetic field generated by the coil can interact with a rotor permanent magnet. Since the outer bottom surface of the insulated cooling pipeline touches the coil of the motor stator, a liquid coolant in the insulated cooling pipeline can cool the coil by means of heat conduction.