Some single layer films of different materials used in the ultraviolet region, which include oxide and fluoride, have been made on the fused silica substrate by resistive heating evaporation or electron beam bombardment technique. According to their transmissivity in 200～2000 nm, dispersion curves of these materials′ refractive index n and extinction coefficient k are obtained. Then their band gap through Tauc plot method and cut off wavelengths are got.