Additional counterweight was chosen to improve dynamic performance of traverse seal mechanism of packaging machine and solve the vibration problem at high speed. Complete balancing analysis of shaking force and shaking moment showed that the mechanism can't achieve complete balancing. According to the theory of mechanism dynamic balancing, complete balancing of shaking force and shaking moment often causes deterioration of other dynamic performance. Optimization mathematical model of shaking force and shaking moment of traverse seal mechanism was established. Simulation analysis was carried out by using MATLAB software and optimal parameters of the model were obtained to improve dynamic performance of the mechanism.