A motor includes a main body and a cooling device. The cooling device includes a mounting seat defining an inlet hole and an outlet hole spaced from the inlet hole, and a cooling pipe communicating with the inlet hole and defining a plurality of ejection holes on a sidewall. The main body includes a rotor sleeved and sealed on the mounting seat. The cooling pipe is received in the rotor. Cooling liquid sprays at the rotor via the inlet hole and the ejection holes, and then the cooling liquid flow out of the rotor via the outlet hole.