Abstract: Manufacturing industry is the foundation of national development. The contact characteristics of machined surface play an important role in the working performance of precision instruments, which directly affects the working accuracy of instruments. In this paper, based on the principle of metal cutting, combined with cutting force and material mechanics characteristics, the size surface height model of turning mechanics is established. Based on the finite element method, the cutting force under certain conditions is modeled and analyzed. The results show that the turning force changes periodically and has certain amplitude. Combined with the analysis of the characteristics of the rough surface of the actual turning surface under different sections, the results show that the surface morphology of the turning surface also shows a periodic change, and there is a certain amplitude; the cutting force and the cutting direction surface morphology remain similar.