The numerical calculation for the model of a multi-ion-beam reactive cosputtering (MI-BRECS) system which we presented very recently in a related paper has been carried out with the parameters adopted in our experiments to prepare PbTiO3 thin films by using Pb and Ti metal targets and MIBRECS technique. The relationships among the sputtered ratio Ri of each target, the partial pressure p of reactive gas in the deposition chamber, and the coverage ratioes Zsmi, Zsli, and Zshi of the simple substances and oxide compounds of Pb and Ti on the substrate surface, with the total reactive gas flux Q and the densities Ji of the sputtering ion beam (both of which can be adjusted independently) are obtained respectively. The calculated results reveal the hysteresis effect which is an essential characteristics in a reactive sputtering, and show that there is a coupling and interaction among the processing parameters in ion beam reactive cosputtering. The relations among the atom ratio and the chemical valences of the elements in prepared thin films with the controllable processing parameters in ion beam reactive cosputtering are obtained, and the method to control and adjust a MIBRECS system for stable reactive cosputtering process is pointed out. The obtained results a-gree with our experiments.