As the key parts of cars, camshafts influences a lot on the quality and durability of cars. Their processing is complicated, time and place consuming and the quality is difficult to guarantee. The turning-grinding composite machine tool (TGCM) for camshafts is studied on basis of ‘process integration with one setup’ theory in this paper. It presents the structure of the turning-grinding composite machine tool by the analysis of the function of TGCM. The revolving working table is used to transfer the turning and grinding function. It also discusses the constant grinding removal rate mathematic model of the cam contour machining. The opened-CNC system for this machine tool is developed by using the VC++6.0 based on PC and UMAC controller. The constant grinding rate model of the cam contour is verified by the experiment results.