The invention provides a device (11) for assisting a cough, based on an oscillation pressure. The oscillation pressure causes a periodic oscillation airflow in a lung system and the periodic oscillation airflow comprises an oscillation exhalation airflow and an oscillation inhalation airflow. The device (10) comprises a controlling unit (11), and the controlling unit (11) comprises:&mdash；a first determining unit (111) for determining whether an inhalation of the lung system is complete, so as to control a valve (13) which is to be closed for isolating the lung system from the external environment,&mdash；a second determining unit (112) for determining whether an internal air pressure in the lung system is larger than a pre-defined pressure threshold, and&mdash；a detecting unit (113) for detecting the start of the oscillation exhalation airflow, so as to control the valve (13) which is to be opened for starting a cough.
