An ECM motor, including: a motor controller and a motor body. A microprocessor of the motor controller is connected to a first temperature detecting unit and a second temperature detecting unit disposed at different positions outside the ECM motor for detecting temperatures at the different positions. In operation, when the temperature difference between the first temperature T1 and the second temperature T2 is smaller than or equal to a preset value T0, a first gear at the rotational speed S1 is selected by the microprocessor and the motor is controlled to run constantly in the first gear at the rotational speed S1. When the temperature difference between the first temperature T1 and the second temperature T2 is larger than the preset value T0, a second rotational speed S2 is selected by the microprocessor and the motor is controlled to run constantly in the second gear at the rotational speed S2.