The surface processing method of CNC workpiece depends on the technical requirements of the surface. However, it should be noted that these technical requirements are not necessarily the requirements specified in the part drawings, and sometimes may be higher than the requirements in the part drawings due to technological reasons. For example, due to the non-coincidence of benchmarks, the processing requirements for the surface of some CNC parts are raised. Or because it is used as a precise benchmark, higher processing requirements may be put forward. After defining the technical requirements for the surface of each CNC workpiece, the final processing method which can guarantee the requirements can be selected, and the processing method which needs several steps and each step can be determined. The selected processing method of CNC parts should meet the requirements of quality, good processing economy and high production efficiency. Therefore, the following factors should be taken into account when choosing processing methods: 1. There is a considerable range of processing accuracy and surface roughness that can be obtained by any kind of CNC processing method, but only in a narrow range is economic, and the processing accuracy of this range is economic processing accuracy. Therefore, when choosing the processing method, we should choose the corresponding processing method which can obtain the economic processing accuracy. 2. Consideration should be given to the properties of materials for CNC workpieces. 3. Consider the structure shape and size of the CNC workpiece. 4. Consideration should be given to productivity and economic requirements. In mass production, advanced technology with high efficiency should be adopted. It can even fundamentally change the manufacturing method of the blank, which can reduce the workload of mechanical processing. 5. Considering the existing equipment and technical conditions in factories or workshops and choosing processing methods, we should make full use of the existing equipment, tap the potential of enterprises, and give full play to the enthusiasm and creativity of workers. However, consideration should also be given to continuously improving existing processing methods and equipment, adopting new technologies and improving technological level.