In order to make bag pick and send accurately, reposefully and fleetly in automatic bag-delivering packaging machine, based on the mathematical model of mechanism for bag-picking, the kinematics characteristics of end actuator were analyzed. The calculation formulas of displacement, velocity and acceleration of end actuator for bag-picking were deduced. Based on the above calculation, the motions and defects of mechanism for bag-picking were summarized and improved. The kinematics curves of bag-picking mechanism were obtained with Matlab and the original results were compared with the improved one. The contrasting result showed that the curves of displacement, velocity and acceleration of modified mechanism for bag-picking were improved. The better kinematic characteristics were gotten and the expected goals were achieved.