Abstract: The interferometric method has been widely used in wavefront sensing of optical systems, however, manufacturing a reference objective with high numerical aperture (NA) has high production costs and risks. The optical interferometric method used in wavefront sensing of the optical system with high NA meets trouble. Using the phase retrieval method, a wavefront testing for optical system with high NA was done and diffraction beam from a pinhole was used as an ideal testing wavefront. The point spread functions (PSF) of wavefront with different frequencies were simulated, and the actual condition need was analyzed. A novel way was introduced into the error analysis, due to the lack of high accurate contrast verification. Wavefront sensing of a microscope optical system has been completed. Through this confirmatory experiment, its results verify this method.