The inclusion of freeform elements in an optical system provides opportunities for numerous improvements in performance.However,designers are reluctant to utilize freeform surfaces due to the complexity and uncertainty of their fabrication.Single diamond turning is a novel machining process capable of generating freeform optical surfaces or rotationally non-symmetric surfaces at high levels of accuracy.In order to achieve good results with this technology some key parameters need to be satisfied.These parameters include tool geometry,tool path generation,tool radius correction,and servo system performance.The servo capacity of slow-tool-servo machine is analysed,and a method to determine tool geometry parameter based on surface analysis is developed.The methods of tool radius compensation and tool path generation to ensure the stability of X-axis are researched.Experiment results show that slow-tool-servo machining technology can be used in preparation of optical free form surfaces element.