Abstract: Because the structure of atypical impeller is complex, so it is impossible to use the five-axis impeller module provided by mainstream CAD/CAM software. When three-axis fixed-directional machining is used in roughing stage, the volume and shape of the residual blank are large and irregular, which seriously affects the efficiency and quality of five-axis machining. In this paper, on the one hand, double cylindrical projection method is used to obtain the driving surface in the open area of impeller, so as to realize 4-axis simultaneous roughing, which has high cutting rigidity and efficiency; on the other hand, in the non-open area, the five-axis simultaneous tool path is obtained by constructing the driving surface, and the tool path is continuous and the tool axis vector has no sudden change. On the other hand, a tool axis vector evaluation method based on NC program is proposed, which can quickly and intuitively evaluate five-axis machining programming. The practical application results show that the tool axis vector optimization method based on driving surface can significantly improve the efficiency and quality of five-axis machining of complex parts.