Abstract: A parallel laser beam splitter was designed based on the characteristics of birefringent crystal for applications such as wavefront shearing interference, dual light beam curved reflective surface measurement and step height measurement. When a plane wave or laser beam enters a birefringent crystal, its mutually perpendicular polarization components will propagate in different states to generate two beams after they exit the crystal. The splitter consists of a single crystal plate. Its splitting principle was described, and the relationship between the splitting distance, the direction of optical axis, the thickness of the plate, and the incidence angle was deduced. The variation law of splitting distance with the main design parameters was analyzed. Lab test was conducted on the splitter, and the analysis results were verified.