We are developing a hard X-ray telescope utilizing multilayer supermirrors. This telescope is conical approximation of the Wolter-I configuration with tightly nested shells. Because of the fact that different nested shell corresponds to different grazing incident angle, so the optimum multilayer design depends on the grazing angle, and one would therefore, ideally design a different coating for each of the nested mirror shells. However, as a matter of practicality, we have to reduce the number of different designs for a reasonable compromise between the complexity of the calculation and optimal performance. In this paper, we investigate the effect of different angular classification on the effective area of the hard X-ray telescope. Many groups of hard X-ray supermirrors are optimized with different grazing incident angles using a numerical and analysis method. These supermirrors are divided into different number of groups, e.g. two, four, six, eight, ten, twelve, fourteen, and sixteen, respectively, and the corresponding effective areas are calculated. Results show that six groups of X-ray supermirrors are suitable for a reasonable compromise between optimal performance and the complexity of the calculation and fabrication.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.