Through the research of CNC lathe automatic programming and machining simulation parameters, summed up in the CNC lathe processing of complex shape programming procedure has advantages, and the complex parts processing as an example, the processing technology and NC program is complete, the use of CATIA V5 R20 plays an important role in the processing of parts. It is beneficial to the improvement of the machining process of the NC programmer, so as to solve the problems encountered in the numerical control machining. It is helpful for enterprises to save time and improve efficiency. The promotion of software automatic programming, so that more CNC practitioners to realize the importance of automatic programming software, and thus stimulate the interest of learning software automatic programming. The importance of automatic programming to the importance of automatic programming and the need for skilled use of automatic programming.