Spectroscopic ellipsometry has been widely used in materials science, microelectronics, physical chemistry and biomedicine. In the spectroscopic ellipsometry system, the degree of polarization of the light source subsystem and the polarization sensitivity of the spectrometer subsystem will affect the measurement accuracy of the spectroscopic ellipsometry considering the leakage of polarizer and analyzer. To remove this systematic error, we included the degree of polarization of light from source and the polarization sensitivity of the spectroscopic ellipsometry in our calibration model; a method for measuring the polarization state of light source subsystem and polarization sensitivity of a spectrometer subsystem is proposed. To verify the method, we present the measurement setup and results for a commercial broadband light source and broadband spectrometer.