This paper makes a theoretical analysis of cam mechanism on the capping machine of beer production line, and using SolidWorks and VB to extract the cam contour line, then obtain the speed, acceleration and pressure angle data of cam and roller follower by combining MATLAB with dynamic analysis. The analysis shows that the cam is unreasonable. In order to improve its performance, three spline curves are used to improve the cam profile. After analyzing the cam profile fitted with three spline curves, the flexible impact of the present cam mechanism is reduced and the performance of the capping machine is improved.