Tin-doped indium oxide (ITO) conductive thin film is prepared on MgF2 substrate by electron beam evaporation. The effect of oxygen and annealing on the sheet resistance and ultraviolet (UV) transmittance of ITO film is investigated. Furthermore,the properties of ITO film are compared with conventional conductive film substrates Au and Cr. The surface morphological image,sheet resistance,microstructure and transmittance curves in the wave band of 190-800 nm are investigated by optical microscope (OM),four-probe method,high resistance meter,X-ray diffractomer (XRD) and spectrophotometer. Variation range of transmittance is acquired in the wave band of 200-400 nm when the sheet resistance reaches 107 Ω. The results indicate that the sheet resistance of thin film prepared with oxygen is higher than that without oxygen;after annealing the sheet resistance of thin film decreases and the microstructure changes from amorphous to polycrystalline. Compared to Au and Cr,the average transmittance of ITO film with the same sheet resistance of 107 Ω or so,which is prepared with oxygen and annealing,is 10% higher in the wave band of 200-400 nm.