In the high precision testing of large aperture aspheric surface, the quality of compensation devices has a direct influence on the result. For the large aperture paraboloid CGH due to its high spatial frequency, the error control is difficult. Through a specific design, the optical field distortion caused by the positioning error during machining is analyzed. In order to reduce the influence of error, the aspherical surface testing is performed by using the double CGH optical path. The separation of the non-operating order diffracted rays of the double compensator and the optical field distortion caused by the positioning error are analyzed. The results show that the maximum spatial frequency of the double CGH is much smaller than that of the monolithic structure, and the RMSE value of the optical field distortion caused by the positioning error is 0. 65 times that of the monolithic structure under the same conditions. It shows that when compensating for testing large aperture aspheric, double compensation CGH element, while meeting the design requirements can well suppress the influence of error caused by the processing.