Vanadium dioxide materials， which show semiconductor-metal phase transition， can be used for protection of photoelectric detectors against laser blinding weapons. The structure， morphology and optical properties of vanadium dioxide thin films prepared by radio frequency magnetron sputtering at different temperatures were reported. The visible to infrared ellipsometric parameters of vanadium dioxide film at 20-100 were measured by an ellipsometer. The optical properties of vanadium dioxide films before the phase transition were obtained by Gaussian and Lorentz model， and the optical properties after the phase transition were obtained by adding a Drude model. The refractive index and extinction coefficient at varied temperatures between 300 nm and 1 700 nm were obtained. The transmittance spectra of 1 550 nm infrared laser at varied power densities show that the threshold power of phase transformation for the VO₂ film is about 12 W/cm²， where the transmittance decreases sharply from 51% to 15%-17%， and the switching rate is about 69%.