Litchi fruit flexible mechanical picking could reduce the loss of fresh fruit, which is the development direction of intelligent mechanized harvesting in future agriculture. According to the agronomic planting of litchi, this paper analyzed its fruit picking requirements, studied the structure of the manipulator's end effector flexible picking and its dynamic transfer, built the structure model of the manipulator automatically picking. By means of simulation software ADAMS, studied the dynamic characteristics of angular displacement, angular velocity, mass center displacement etc attached to each joint component in picking process, the simulation of the joint driving torque compared with the theoretical calculation showed the error is less than 3%. Thus, it was proved that the simulation design of litchi flexible picking manipulator met the work requirements of flexible picking, and could provide the theory reference for prototype design.