As the core component of high-performance space cameras, off-axis mirrors can be used to realize the design of space cameras with large fields of view and long focal lengths. The high-precision surface map is the guarantee of high-quality imaging of space cameras. In order to solve the high-precision surface map testing of off-axis aspheric mirrors and ensure the imaging effect of space remote sensing cameras, a high-precision surface map testing method for off-axis aspheric mirrors is established based on computer generated hologram optical components, and the high-precision testing of off-axis aspheric mirrors is realized. This provides the necessary conditions for the fabrication of ultra-precision optical systems.In order to improve the utilization of light energy and improve the detection accuracy, the off-axis aspheric surface was moved to the axis by adding translation and tilt to carry out the null compensation design. This method can avoid the compensation design of the coaxial parent mirror corresponding to the entire off-axis aspheric surface, so as to greatly improve the energy utilization. The spatial position of the mirror to be measured can be determined by designing the reference spot, the interference testing of the mirror to be measured can be realized with high precision through aberration adjustment, and the interference diffraction order can be effectively separated by using the carrier frequency, so as to achieve high-precision measurement of the mirror surface to be measured.Null compensation design is performed by adding translation and tilt to move the off-axis aspheric surface onto the axis. It avoids the compensation design of the whole coaxial mirror corresponding to the entire off-axis aspheric surface, thus greatly improving the energy utilization. The relevant design results are shown in Figure 3-Figure 8. The author conducted a detailed analysis of the optical path structure, including the spatial relative positions of the interferometer, the CGH, and the off-axis aspheric mirror. To properly position the aforementioned optical components, auxiliary zones were designed to achieve precise alignment among them. The fitting residual of the main zone is zero, indicating that the design accuracy meets the requirements of the test results. The fringe density in the main zone does not exceed 137 lp/mm, with a periodic spacing of no more than 7.3 μm, which meets the fabrication capability of laser direct writing systems and enables high-quality patterning of CGH fringes. The alignment zone pattern was designed using the +3rd diffraction order, featuring an annular fringe configuration. With a fringe density not exceeding 251 lp/mm and a periodic spacing no greater than 3.98 μm, this design remains compatible with laser direct writing systems for high-precision fabrication. Additionally, during testing, the diffraction spots of various orders can be fully separated. This effectively prevents light from other diffraction orders from interfering with the measurement results as stray light during testing.A high-precision surface map testing method for off-axis aspheric mirrors are proposed based on computer generated hologram optical elements. By adding translation and tilt to move the off-axis aspheric surface to the axis for null compensation design, this method effectively avoids the null compensation design of the whole coaxial mirror corresponding to the entire off-axis aspheric surface, so as to greatly improve the energy utilization rate of the system. Combined with engineering examples, it analyzes in detail how to consider the precise alignment of each optical element, how to effectively separate each diffraction order in the design of the main region, and how to design the fringe density of each region in combination with the actual manufacturing level when using the design method for off-axis aspheric compensation design. From the design results, it can be seen that based on the method, the null compensation design for off-axis aspheric surface can be effectively realized, and the establishment of this method will provide some technical support for the manufacturing and testing of high-precision optical systems.