Abstract: In this article, a cone error variation model is established based on the small displacement torsor method, and the variation of cone contour error is analyzed. The Monte Carlo simulation method is used to solve the actual variation range of various spinor parameters in the conic contour error model and compare it with the ideal variation range. Based on the response surface method, the functional relationship between the actual variation range of each error component and the taper and dimensional tolerance is fit, and then the modeling accuracy of the model is tested by using complex correlation coefficients. The conical error model established based on the small displacement screw method provides a theoretical basis for analyzing the error transmission process and tolerance optimization of assembly bodies.