At present, aspherical elements are usually used to improve imaging quality and degrade complexity of system in the high numerical aperture (NA) projected lithography objective. However, high-precision aspherical surface testing has been a major problem in the field of optical detection. It is also the key factor which restricts the fabrication of high NA projected lithography objective. To solve this problem and aim at high NA projected lithography objective in the even of a high order asphere, the relationship and the calculating method between the phase and spatial frequency of computer-generated hologram (CGH) are discussed in the paper first. Then, by using a point source illumination mode, the methods of choosing key CGH design parameters and avoiding the interference of non-working order diffraction rays are analyzed in detail. Lastly, a CGH is fabricated using the design parameters chosen from this paper, and the asphere is tested by this CGH precisely. The root mean square value of the aspheric surface′s convergence precision eventually reaches 0.46 nm after several fabricating and testing iterations.