Abstract: The dynamic error of servo system is an important effect on trajectory precision of robot end-effector. In this paper. Using D-H notation, the coordinate frame of adjacent links has been set up. On the basis of the kinematics analysis, the model has been derived, which describes the relationship between derivation of angle of robot axes and trajectory precision of robot end-effector, by differentiating the homogeneous transformations. In working space of robot, many typical trajectories have been chosen. During robot motion along these typical trajectories, through series communication of robot, the encoder pulse of robot axes has been acquired. Using the model, the quantitative evaluation for trajectory precision of robot has been provided after the data processing