The invention relates to the technical field of medical treatment, in particular to an auxiliary sputum excretion method for a non-invasive ventilator and the non-invasive ventilator, and solves the technical problem how to help non-invasive ventilation patients excrete sputum. According to the auxiliary sputum excretion method for the non-invasive ventilator, during the normal mechanical ventilation for the patients by the non-invasive ventilator, after it is determined the patient needs sputum excretion, the sputum excretion operation is started in each respiratory cycle of the patient, andthe sputum excretion operation is not stopped until it is determined that the patient needs to stop sputum excretion. The non-invasive ventilator comprises inspiration and expiration branches, positive and negative pressure air sources, a sensor unit and a control unit, the sensor unit monitors physiological data used for determining whether or not the patient needs sputum excretion and needs to stop sputum excretion, the control unit analyzes the physiological data monitored by the sensor unit to determine whether or not the patient needs sputum excretion and needs to stop sputum excretion, after it is determined that the patient needs sputum excretion, the positive and negative pressure air sources are controlled to perform the sputum excretion operation, and the sputum excretion operation is not stopped until it is determined that the patient needs to stop sputum excretion.