The invention relates to a chemical ionization-vacuum ultraviolet single photon ionization composite ionization source device based on air discharge. The device comprises a vacuum ultraviolet lamp, discharge electrodes and other electrodes of an ionization chamber cavity, wherein a pair of discharge electrodes are arranged immediately below the vacuum ultraviolet lamp, a certain direct current voltage is applied to the vacuum ultraviolet lamp to cause a discharge between the vacuum ultraviolet lamp and the discharge electrodes; in the ionization chamber cavity, a plurality of ion extraction electrodes and differential aperture electrodes are arranged in parallel and spaced apart below the discharge electrodes, through holes are formed along the axis direction of the electrodes, DC voltageis sequentially applied to the electrodes, and electrodes are connected with each other through precision resistances having the same resistance value; a sampling capillary is arranged on the wall ofthe ionization chamber cavity between the discharge electrodes and the adjacent ion extraction electrodes, a vacuum pump suction port and a vacuum gauge interface are additionally provided; and a certain DC voltage is applied to the vacuum ultraviolet lamp to illuminate the vacuum ultraviolet lamp. The device is small in size, low in power consumption, simple in structure and easy to integrate.