Based on the reflection principle of polarized light and measurement of multi-angle multi-fitting algorithm, the accurate measurements of the refractive indexes and thicknesses for the film materials are achieved. When highly collimated diode laser incidents on the interface between thin films and air, the curve of reflectivity varying with the incident angle is obtained by gradually rotating the sample or changing the incident angle of the sample surface. Multiple solutions of film thicknesses and refractive indexes can be solved by using reflectivities from the different angles in this curve based on calculation formula. Its optimal solution can be determined by fitting measuring and corresponding computational reflectivities. By multiple expanding the scope of the film parameters and then fitting them, more accurate film parameters can be found out. The refractive index and thickness of the SiO2 film are measured using this method, of which error of refractive index is less than 0.3% and thickness error is less than 0.07%.