Based on radiometry，electromagnetism and polarization theories and the Fourier transform spectroscopy，an in-depth study is conducted on the SNR of the self-developed ultra-compact static polarization interference imaging spectrometer (USPIIS) theoretically and experimentally. The theoretical equations of its SNR are deduced. Under paraxial approximation，the curve of the SNR changing with incidence angle is given via computer simulation. How the polarizing directions affect the SNR of USPIIS，which is a particular feature of the polarization interference imaging spectrometer，is deeply studied. When modulation depth equals 0.6，0.7，0.8，0.9 and 1.0，the curves of the SNR changing with polarizing directions are given respectively; after which the optimum value is recommended. Under optimum conditions，the changing laws of SNR with the elements of detector are obtained，which turned out the same as the prediction of the theory. The theoretical and experimental results both indicate that the novel imaging spectrometer has the properties of high throughput and high SNR under the condition of high modulation depth，which is suitable for aviation，remote sensing，weak signal testing applications. The work can provide theoretical basis and guidance for the design，development and engineering of polarizer，interferometer and polarization imaging interferometer.