According to the structural features of food sorting robots with six degrees of freedom, kinetic theory analysis was carried out by using Lagrange approach. Virtual prototype modeling was established, and the curves of angle, angular velocity, angular acceleration, moment and power were obtained by rigid body dynamics simulation within ADAMS. The results showed that the robot had a good motion stability and dynamic response, which in addition provide a theoretical basis for motor selection. Coupled dynamics simulation was also carried out by SimDesigner, which demonstrates the rationality of the manipulate design.