The invention discloses an ion source suitable for a flight time mass spectrometer, which relates to an ion source for a mass spectrometer. The ion source is provided with a sample introduction booster pump, a solenoid valve, a repulsion electrode, an ionization chamber, a middle grid, an extraction grid, a focusing electrode, an emergent pole piece and an excitation source generator, wherein theoutlet of the sample introduction booster pump is communicated with the inlet of the solenoid valve; the outlet of the solenoid valve is communicated with the inlet of the repulsion electrode; the repulsion electrode is arranged in the inlet end of the ionization chamber; the middle grid is arranged at the outlet end of the ionization chamber; the extraction grid is arranged at the side of the middle grid; the focusing electrode and the emergent pole piece are successively arranged at the side of the extraction grid; the focusing electrode and the emergent pole piece are both provided with a central ion extraction through hole; the ionization chamber, the repulsion electrode, the middle grid, the extraction grid, the focusing electrode and the emergent pole piece are coaxial; a filament is arranged out of the upper end and the lower end of the ionization chamber; and the excitation source generator faces to an energy beam incidence hole arranged on the ionization chamber. According tothe ion source, a pulse ion group can be generated, the ion extraction efficiency is greatly improved, the ion use ratio is improved, and the sensitivity of the mass spectrometer is improved.