In order to quantitatively evaluate and reasonably design a wire grid (WG) polarizer applied to airlight rejection, a performance characterization method for a WG polarizer is proposed. The method combines rigorous coupled- wave(RCW) analysis and a computational model for performance of airlight rejection utilizing polarization filtering. In the proposed method, RCW analysis is responsible for calculating TM and TE polarization transmission efficiencies. The proposed method is utilized to calculate and analyze the performance of airlight rejection utilizing a dimensional and rectangular WG polarizer and the reached conclusion is that gold (Au) and copper (Cu) grating outperform silver(Ag), aluminum (Al) and chromium(Cr) gratings; the performance of airlight rejection utilizing a WG polarizer is improved with increasing gratings height; the relatively optimal grating height is above 200 nm; the relatively optimal range of a grating period is 200~300 nm; the performance of airlight rejection utilizing a WG polarizer increases with increasing duty cycle of gratings. The designed parameters for a WG polarizer are the grating material of Cu, substrate material of silica(SO₂), duty cycle of 0.5, grating period of 250 nm and grating height of 200 nm.