An analysis of multifrequency A-O deflections and diffraction grating for multibeam-splitting techniques applied in the optical disc storage is given in this paper. Based on the theory of binary computer-generated holograms, accurate periodic parameters of a phase grating which can generate equal-intensity multiple beams are obtained by using pulse position modulation in terms of computer analogue. According to the parameters, a phase grating has been fabricated by a special method. The phase grating has a total diffraction efficiency of 73% with the masxmum residual deviation of 1.75 % from the average, which can meet the practical usage.