The composition, working principle and technical requirement of automatic vertical packaging machine are discribed.The transmission systems and eccentric sprocket with variable speed are designed. Applying dimension-driven technology and “formula” function of Solidworks software, parametric design and modeling of automatic vertical packaging machine are realized. The simulation results show that larger drive sprocket limit angle can be obtained by increasing center distance of eccentric sprocket mechanism, and the heat sealing point of transverse sealing mechanism and sprocket offset corresponding packet length can be determined from the output movement characteristics of eccentric sprocket mechanism, this can improve the design quality and efficiency of products．