Aiming at the requirement of higher accuracy of positioning in industry and metrology,a positionning method is proposed based on polarimetric interferometer. In this interferometric system,a polarimeter combined with polarization beamsplitter and polarizer has replaced photo-detector. The fringe interpolation of output laser beam can be reached at 36 000,for a 633 nm laser source,the potential theoretical resolution is 10 pm. The measurements have both carried out by own-developed polarimetric interferomete...