The work aims to reflect the dynamic characteristics of web paper folding mechanism and the dynamic contact excitation between machete and paper accurately.Based on the rigid-flexible coupling theory, a rigid-flexible coupling dynamic model of the web paper knife-type folding mechanism was established. With the machete arm and the paper as flexible bodies, the rigid-flexible coupling dynamic characteristics of the folding mechanism were studied. The kinematic analytical model of the rigid folding mechanism was established. The displacement, velocity and angular velocity of the followers at the joint of the connecting rod and the machete arm were obtained and compared with the rigid-flexible coupling analysis value to verify the rationality of the rigid-flexible coupling model. Then, the relationship between the deformation of the machete arm and the lateral displacement of the machete head was analyzed to determine the maximum rotation speed of the folding mechanism to ensure the folding accuracy. Furthermore, the dynamic contact excitation between the machete and the paper was analyzed, and the working loads of the machete were determined. Finally, the dynamic analytical model of the rigid folding mechanism was established. Compared with the analytical values of the rigid-flexible coupling model, it was found that when the rotation speed of the folding mechanism was greater than 25 000 r/h, the deviation of the two support reaction forces was significant. Therefore, the effect of the machete arm deformation should not be ignored. The study has certain reference value for simulation and experimental research of web paper folding mechanism.