Multi-component nitride TiAlN films were deposited on high speed steel substrate through the reactive sputtering process. A model was successfully developed for simulating the deposition of TiAlN. By following this model the deposition rate and nitride coverage fraction at various nitrogen rates and sticking coefficient of species were simulated. The simulated deposition rates at different nitrogen flow and sputtering current are in good agreement with the experimental results. A stoichiometric TiAlN coating formed at the critical nitrogen flow rate and no obvious compositional changes were observed with further increase of nitrogen flow rate. The different reaction kinetics of Ti and;Al with nitrogen was used to account for the optimum properties of TiAlN films developed at relatively high nitrogen flow rate.