In the processing center, CNC lathe generally needs to use more than one tool, so we should arrange the processing order reasonably, which is conducive to improving the processing accuracy, processing power and economic benefits. When arranging the NC lathe processing order, we should follow the general technological principles of "first base plane", "first face then face", "first priority then second" and "first rough then fine". The selection of positioning datum directly affects the arrangement of processing order. As a positioning datum, the surface should be processed well in order to provide a reliable positioning datum for other processing areas. Because the surface machined by this process after selecting the positioning datum may be the positioning datum of the next process, after the determination of the positioning datum of each process, the roughly second order of the whole process can be deduced step by step from the finishing process after all. When deciding the processing order of NC lathe, it is necessary to clarify whether the parts should be pre-processed before processing. Prefabrication usually ends with a general machine tool. If the precision of the blank is higher, the positioning is more reliable, or the processing margin is sufficient and uniform, it can be processed directly on the processing center instead of pre-processing. At this time, according to the accuracy of rough benchmark, we should consider the difference of process in the machining center, so one process or several dividend processes can be completed. When CNC lathe processes parts, it is difficult to guarantee the standard between the machined and non-machined surfaces, which is the same as CNC milling. Therefore, even if the right and wrong processing surface is required by the drawing, it is necessary to add appropriate margin on the non-processing surface when making the blank, so as to ensure that the standard between the non-processing surface and the processing surface meets the drawing requirements in the machining center. Similarly, if there is a standard requirement between the pre-fabricated surface before CNC lathe processing and the faceted surface processed by CNC machining center, a certain amount of processing allowance should also be left during pre-fabrication. It is better to finish all processing contents including pre-faceted surface in a clamp of the machining center.