In the process of an asphere fabricating, the part with large mapping distortion in the large caliber off-axis asphere may not be measured by an interferometer due to larger interferometric fringe density. To solve this problem, the parameter named related distortion was used to describe the mapping distortion quantitatively, and a Computer Generated Hologram(CGH) with higher freedom and stronger compensation ability was designed. By taking the mapping distortion distribution into account, the method selected a proper path and allowed all the aspheric surface to have smaller mapping distortion in the design of the CGH. With the method, a CGH with proper paths was designed for testing the 1.45 m off-axis asphere, by which the full map distortion of the system is less than that of the traditional null-lens compensator. The test experiment shows that the designed CGH can test the full map error of the off-axis asphere, which verifies the validity and practicability of the proposed CGH design method and demonstrates that designed CGH with considering test mapping distortion has solved the problem as mentioned above. By this method, the map errors of 1.45 m diameter off-axis asphere are 0.374λ PV and 0.023λ RMS now.