Abstract: Compute-generated hologram is used as a compensator in off-axis holographic detection system to test large concave aspheric surface more precisely.According to the principle of the off-axis holographic detection system using CGH.the calculation and making of CGH are analyzed.The measurement of concave aspheric surface with an aperture of 150 mm, spherical radius of 1 499.7 mm and aspheric coefficient of -1 is performed.The measurement result is coincident with the result of profilograph.