In order to determine the optical constants of fluoride films in deep ultraviolet (DUV) to ultraviolet (UV), high-refractive-index materials such as LaF3, NdF3, and GdF3, and low-refractive-index materials such as MgF2, AlF3, and Na3AlF6 single thin films are deposited by a resistive-heating boat at different deposition rates and specific substrate temperatures on JGS1 and single crystal MgF2 substrates. Transmittances in 190～500 nm of all fluoride thin films are measured through business spectrometer in the ambient atmosphere. The optical constants of these films are determined from iterative algorithm combined with the envelope method. These dispersive optical constant values are fitted by Cauchy formula and index formula, respectively. The results are consistent with other relevant articles, which testifies the reliability of the results.