Abstract: Since the crystal ZnSe is soft and low transparent, a thin-film coating must be deposited on its surface to increase its transparence and machine strength. A method of depositing anti-reflection film on the surface of ZnSe substrate is introduced, which adopts ion source to deposit zinc sulfide (ZnS) as a combinative layer of crystal zinc selenide (ZnSe). The two kinds of different fluoride material were evaporated as a low refractive index and protective layer by using the total evaporation technology. A film system which meets the standard of environment and rigidity was prepared. Besides, its average transmissivity attains to 98% at the range of 3μm～5μm.