In order to solve the problem on alien thread machining, the method of automatic computer numerical control (CNC) programming is researched. The flowchart for intelligent programming based on Edgecam software was proposed, the key technology of processes planning, software design and programming were discussed, the program were written by using PCI and PDI which are the secondary development language in Edgecam, finally, the case study used by arc thread in typical part validated the proposed method. Reference is provided for intelligent programming for the manufacturing intelligently and rapidly in other parts.