Abstract: Provided is an ion source system for an atmospheric pressure interface, comprising an atmospheric pressure ion source (1), wherein the atmospheric pressure ion source (1) is connected downstream to a vacuum ion source (2). Also provided is a mass spectrometer, using the present ion source system as an ion source. The present ion source system uses a combination of the atmospheric pressure ion source (1) and the vacuum ion source (2), is suitable for test sample having variety of forms, and performs secondary ionization on a sample to be tested, thus enhancing ion transmission efficiency. The present mass spectrometer significantly increases ion transmission efficiency, thus enabling continuous injection of samples and testing, and increasing the scanning speed of the spectrometer, particularly suitable for miniaturized mass spectrometer.