Mechanical models of heat sealing and cutter mechanism of bag machine were established and simplified according to their motion characteristics. Based on the constraint equation obtaining from heat sealing components motion, analytical expressions of heat sealing location, velocity and acceleration were obtained. The validity of kinematic relations was verified through analysis of examples and Pro/ E simulation. Optimization analysis of acceleration of heat sealing components was carried out on the basis of ensuring fixed route. The results showed that changing the design parameters of components can decrease the maximum acceleration of heat sealing components. The purpose was to provide academic foundation for dynamics and vibration analysis.