Abstract: Two models used in computing gas discharge——PIC model and fluid model are compared. The initial pseudospark discharge is simulated with PIC model and the properties of the three ionization growth regimes are presented. The virtual anode formation time and propagation velocity at different pressures with different cathode apertures are calculated. The formation of virtual anode is accelerated, as well as its propagation towards hollow cathode either at higher pressure or with larger-diameter aperture.The formation of virtual anode effected by hollow cathode is investigated at different pressures. The results show that the effect of hollow cathode plays a more important role in initial discharge at low pressure.