Dual ion beam sputtering technique for deposition of AIN thin films is described. The metal atom flux was supplied on substrate by sputtering an Al target with an Ar ion beam, while the reactive N₂ flux was supplied directly on the growing film surface as a nitrogen ion beam. In this experiment, it is clear that the AIN thin films with high optical transparency(>95%) in the wide wavelength regions, high refractive index(>2.3) and (110) plane preferential orientation are obtained on substrate at 25°C by the control of nitrogen ion beam energy irradiating to the growing film surface.