Abstract: Sawing diamond is a cutting method with high processing precision. Diamond cutting machine is used to cut natural diamond, and then the sawing diamond cutting surface is detected and analyzed by optical microscope, roughness measuring instrument and X-ray diffractometer. The surface morphology, roughness and crystal image of natural diamond (100) crystal surface are obtained. The results show that tool trace is the main factor affecting the quality of natural diamond sawing surface processing. It is also found that isomerization of carbon occurs on the surface after cutting and generates a non-graphitizing carbon allotrope, whose content on the surface of the tool trace is 8.3% but 2.0% on smooth surface. Good natural diamond cutting surface can be obtained by normal sawing method.