DM feature based CNC machining automatic programming technology for rotational parts is studied. Dividing part hierarchy and feature hierarchy analysis method is put forward in CNC machining auto-programming. Algorithms about how to realize feature hierarchy or part hierarchy automatic programming cutting are given such as transverse, lengthways, isometric and concave profile machining cycles. An innovative Boolean calculation interference flag method is used in turning isometric algorithm. One-to-one mapping of creating tool pathways algorithm to machining process step is expediently to get diversiform machining project from part profiles.