Antimony selenide (Sb2Se3) films are widely used in phase change memory and solar cells due to their stable switching effect and excellent photovoltaic properties. These properties of the films are affected by the film thickness. A method combining the advantages of Levenberg-Marquardt method and Spectral Fitting Method (LM-SFM) is presented to study the dependence of refractive index (RI), absorption coefficient, optical band gap, Wemple-DiDomenico parameters, dielectric constant and optical electronegativity of Sb2Se3 films on their thickness. The results show that the RI and absorption coefficient of Sb2Se3 films increase with the increase of film thickness, while the optical band gap decreases with the increase of film thickness. Finally, the reasons why the optical and electrical properties of the film change with its thickness is explained by XRD, EDS, Mott-Davis state density model and Raman microstructure analysis.