Objective To make bag opening and blanking more precise, more stable in automatic bag packaging machine. Methods Based on the mathematical model of mechanism for bag opening, the kinematics characteristics of executive link were analyzed, base on the coordinate matrix transformation, the calculation formulas of displacement, velocity and acceleration of executive link for bag opening were deduced, and Matlab was used to carry out the kinematics simulations, getting the kinematics curves of bag opening mechanism. Results The lifting velocity and acceleration curve as well as the rotation velocity curve was continuous, while the rotation acceleration curve was discontinuous, with a small peak acceleration. Conclusion The results of kinematic analysis showed that the double cam-linkage combined mechanism as actuator of bag opening station, can finish the motion track of bag opening mechanism end-effector, and the expected function of bag opening mechanism can be better realized.