At high speed, the calculated result has deviation compared with that of practical situation if the smaller stiffness parts are regarded as pure rigid body. Based on rigid-flexible coupling dynamic theory, a dynamic model of pusher device system with rigid-flexible coupling of a packaging machine was built in the finite element method and modal superposition method, and the smaller stiffness parts were softened. The dynamic stress of the pushing hands during pushing and folding procedures were calculated according to the above model. The validity of this method was verified by comparing the results with the conclusion in ABAQUS. A comparative study of the pusher device's multi-rigid-body calculation model and rigid-flexible coupling dynamics model has shown that the distortion of flexible pushing hands causes positional deviation, which verifies that the calculation result of the rigid-flexible coupling dynamics model is more accurate at high speed.