Abstract: SiO₂thin film was successfully prepared on sapphire substrate by RF magnetron reactive sputtering method with silicon as the target and oxygen as the reactive gas.The influences of parameters such as oxygen content RF power and the sputtering pressure on the film deposition rate were analyzed experimentally.The composition of the film was studied and infrared optical property of the film was tested.The results showed that the electron binding energy of silicon and oxygen elements was same as those of in compound SiO₂.SiO₂films can be obtained on sapphire by RF magnetron reactive sputtering method.The deposited SiO₂film has a highly antireflective effect on sapphire substrate.