Convex aspheric surface is tested by a circular amplitude computer-generated hologram (CGH) fabricated with our equipment and techniques, and much research work has been done simultaneously. However, the analysis of the detailed characters of the CGH used in the test system has not been systematically given in detail, including the correct phase, amplitude, and filter condition of the CGH. The calculation equation of the proper duty circle and the phase of the CGH are deduced, the frequency filter condition of the different diffracted orders of the CGH is demonstrated, and the deduction results are validated by the related experiment. The conclusion can help us to determine the radius ratio of the uncontrolled area over the full aperture of the aspheric surface during the process of optical system design, and it also points out that the radius ratio can be reduced by adjusting the radius of curvature of the reference surface and the distance between the reference surface and the convex aspheric surface. The work can assist us in designing the test system efficiently and correctly with CGH.