In the process of machine tool cutting, there are strict geometric relations among the cutting edge curve / tool surface, machine tool movement and workpiece surface, and the machine tool movement is also related to the type of tool. Firstly, the forming methods of cutting workpiece surface are analyzed and summarized from the geometric point of view, and the scanning forming method and its geometric expression are studied, and the research technical route of forming turning scanning forming is put forward. Then, the mathematical modeling and Simulation of forming turning are carried out according to the proposed technical route. Finally, taking the groove of the inner ring of the formed turning ball bearing as an example, the mathematical modeling of the design surface of the workpiece and the machined surface of the workpiece is carried out. The radial dimension changes of the workpiece caused by the cutting force and tool wear are analyzed, and the simulation of the machined surface of the workpiece is carried out.