A modified model describing the changing ratio of vanadium to oxide on the target and substrate as a function of oxygen flow is described. Actually, this ratio is extremely sensitive to the deposition conditions during the vanadium oxide (VOx) reactive magnetron-sputtering process. The method in this article is an extension of a previously presented Berg's model, where only a single stoichiometry compound layer was taken into consideration. This work deals with reactive magnetron sputtering of vanadium oxide films with different oxygen contents from vanadium metal target. The presence of vanadium mixed oxides at both target and substrate surface produced during reactive-sputtering process are included. It shows that the model can be used for the optimization of film composition with respect to oxygen flow in a stable hysteresis-free reactive-sputtering process. A systematic experimental study of deposition rate of VOx with respect to target ion current was also made. Compared to experimental results, it was verified that the theoretical calculation from modeling is in good agreement with the experimental counterpart.