Impeller is the core part of the engine. Because of its complex shape and structure, it is a typical difficult to machine part. Generally, five axis machining is used. In this paper, CATIA software is used for 3D modeling of a certain type of impeller, the tool path is optimized, the post-processing program is generated, and then VERICUT is used to simulate machining. Finally, it is proved that the method of combining CATIA with VERICUT to process complex parts is feasible.