In ultra-precision machining,the major factors influencing the surface topography of workpieces include many parameters of cutting process such as the tool geometry,feed rate,the speed of spindle and relative vibration between the tool and the workpiece.A surface topography simulation model of ultra-precision machining is established considering these factors.Trimming phenomenon of the tool edge profile is also analyzed at the radial section of the workpiece by the simulation program.It is experimentally shown that good effect is obtained by using the model to simulate the surface topography of ultra-precision face turning.The model can also be used for simulating the traces of tool motion,predicting the three-dimension microscopic surface topography and two-dimension section profile,and optimizing the cutting parameter for diamond turning process.