Abstract: Optimization design of partially compensating lens is one of the key problems for large aperture convex aspheric surface testing using partcompensating lens and subaperture stitching. A design method for the partcompensating lens based on ZEMAX was proposed, which took the slope of wavefront as the optimization objective, and optimized the lights on the full aperture by observing the radius of dispersive spot. The results indicate that, the large aperture convex aspheric surface can be tested by a simple single partcompensating lens. In different areas of the sub aperture, the maximum radius of the dispersive spot in the ideal focal plane is less than 165 μm, which can always achieve the requirement, verifing the feasibility of testing the large aperture convex aspheric surface by partcompensating lens and subaperture stitching.