The Principle of a novel polarization interference imaging spectrometer (PIIS) is described and the shearing and imaging principle of the PIIS is analyzed. Influence of polarized direction of polarizer and analyzer on modulation depth of spatially distributed interferogram is analyzed and calculated. The dependence of modulation depth on deviation is calculated with polarized direction deviating from the ideal direction. Spatial curved surface of variation of the modulation depth with deviation and spatial orientation of polarizer′s polarization direction in the case of the maximum modulation depth (V=1) or minimum modulation depth (V=0) are given and discussed.