Abstract: The ultra-precision diamond turning is a significant way to manufacture high- precision diffractive optical elements (DOE); however, this way is unable to achieve compensation machine currently that results in lower machining accuracy. Based on the study on the process of diamond turning and the compensation of surface shape error, and on the analysis of actual measurement data by the surface profile, the normal residual error was calculated between the actual turning curve and the ideal curve to get new machining trace of diamond turning in this paper. The compensation test on DOE of 78 with the diamond turning machine was done, and finally the value of peak value (PV) converges rapidly from 10.4 m to 4.3 m.