A motor drive circuit including a back electromotive force detecting module and a processing module is disclosed herein. The back electromotive force detecting module is electrically connected to a single phase DC motor and is configured to detect a back electromotive force of the single phase DC motor and to output a detecting signal correspondingly. The processing module is electrically connected to the back electromotive force detecting module and the single phase DC motor. The processing module is configured to determine the rotation direction of the single phase DC motor according to the detecting signal and a hall signal outputted by a hall element located in the single phase DC motor, and is configured to control the single phase DC motor.