Computer simulation of reactive sputtering was carried out to explain the enhancement of the deposition rate of complete oxide film using reactive gas flow modulation. The model dealt with the preparation of TiO2 film with a titanium target and oxygen in rf reactive sputtering. The computed results showed good agreements with the experimental data obtained in our previous work. The effects of the flow modulation were elucidated with the calculated timewise variations for partial oxygen pressure and target coverage. The effects of modulation patterns were also evaluated using the simulation.