The broad-spectrum Mueller matrix ellipsometry can achieve nanometer-scale film structure measurements in the range of visible spectrum by fitting the wide spectral polarization parameters and dispersion of samples. COMSOL can simulate optical processes in multiple physical fields. Therefore, the combination of COMSOL simulation and broad-spectrum ellipsometry is able to achieve high-precision measurement of thin film structures in multi-physical field. In this paper, firstly, the ellipsometry parameters of SiO2 film on silicon substrate are measured by a broad-spectrum ellipsometer. Secondly, the reflection process of SiO2 film on silicon substrate is simulated by COMSOL. Then, the Mueller matrices of the samples were calculated respectively, and the thickness of the SiO2 film was obtained by comparing the matching degree of the two Mueller matrices. Finally, the experimental and simulation results of Mueller matrices M12, M33 and M34 with different thickness of SiO2 film is analyzed and compared comprehensively. The results verify the feasibility of the measurement method combining Mueller matrix ellipsometry with COMSOL simulation, which can broaden the application of multi-physics field measurement of broad-spectrum ellipsometry.