Abstract: Plasma characteristics of a pulsed vacuum discharge hydrogen ion source are investigated.A one dimensional numerical dynamic collisional radiative atomic and molecular (CRAM) model is suggested to simulate the micro physical process during the pulsed discharge. The evolutions of all nine species' population number densities and three main parameters, electric field intensity, electron temperature and gas temperature, along time and axis are calculated. The results indicate that large population number densities exist near the anode of hydrogen ion source, and the hydrogen ion density is about 93.9% of the total ion densities which is reasonably in agreement with that from references. The spectral line intensities of the first three atomic lines in Balmer series ( n =3,4,5) obtained from the above CRAM are reasonably in agreement with that from references too.