A motor, a cooling device, and a cooling method are disclosed. The cooling device is mounted on a stator of the motor. The cooling device includes a sleeve and a spiral duct. A wall of the sleeve has a spiral groove extending along the sleeve. The sleeve is sleeved onto the stator. The spiral duct is mounted in the spiral groove. The spiral duct has a first spiral form corresponding to the spiral groove, so that the spiral duct is correspondingly installed in the spiral groove. The spiral duct has a second spiral form extending along the spiral duct. A twisted spiral cooling channel is formed along the spiral pathway. A cooling fluid flowing through the twisted spiral cooling channel is subjected to the continuously changing cross-section of the twisted spiral cooling channel to enhance the swirl intensity, thereby improving the convection heat transfer effectiveness.