The utility model discloses a non-invasive ventilator with an inhale/exhale positive airway pressure ratio capable of being reversely adjusted. The non-invasive ventilator with the inhale/exhale positive airway pressure ratio capable of being reversely adjusted comprises a mask and a turbine, wherein the turbine is communicated with the mask through a ventilation pipeline, an electromagnetic valve is arranged on the ventilation pipeline, the electromagnetic valve adjusts pressure and the flow rate output by the ventilator and reduces the minimum IPAP/EPAP to be zero. The non-invasive ventilator with the inhale/exhale positive airway pressure ratio capable of being reversely adjusted achieves rapid switching between the IPAP and the EPAP, solves the problem that the IPAP can not be lower than the EPAP, and provides an optimal optional scheme for early treatment of the sleep apnea hypopnea syndrome and the chronic obstructive pulmonary disease.