Based on the effect of the polarization state of polarized light and the degree of polarization on the second-order correlation function, the influence of light polarization on visibility and signal-to-noise ratio (SNR) is investigated by use of the statistical optics theory. It is shown that only the polarization degree has effect on thermal light correlated imaging. The visibility of correlated imaging is a quadratic function of the polarization degree. An increase in the polarization degree leads to an increase in the SNR of conventional correlated imaging, but the SNR obtained by substracting the background and using the second-order coherent degree is independent of polarization degree.