The present invention provides a device (1) for assisting a cough comprising a hosing (3), a chamber (5) formed in the housing, a mouthpiece (7) communicating with the chamber and exposed out of the housing, and an electromagnetic valve (9) assembly for opening or closing the chamber at a pre-set frequency. The device for assisting a cough according to the present invention may produce a high cough pressure and thus form a strong cough airflow to loose and cough the lung mucus out of the airways, and may prevent the collapse of the patient's airway caused by the rapid release of the cough pressure.