Hydrogenated amorphous silicon (a-SiH) thin film is a technologically important material in microelectronic and optoelectronic industry, and ellipsometry is one of the important thin film characterization tools. The effects of different optical models including Tauc-Lorentz (TL) model and Forouhi-Bloomer (FB) model on the structural and optical results of a-SiH thin film in ellipsometry analysis are investigated. It is indicated that the measured thin film thickness, roughness and optical constants using different models are inconsistent. The thin film thickness from TL model is closer to the one from scanning electron microscopy (SEM) and the roughness is more comparable to the empirical value corresponding to atomic force microscopy (AFM) result. Combining the published references, it′s found that the varied thin film thickness and roughness are due to the different optical descriptions. Meanwhile, under the condition of different mathematical processing and assumption, the difference between optical constants from FB model and TL model appears.