Currently, motion control algorithms of lower limb exoskeleton robot had errors in tracking desired trajectories of human hip and knee joints, resulting in poor follow-up performance of the human-robot system. Therefore, this paper proposed Iterative Learning Control Algorithm to track the desired trajectory of human hip and knee joints. Firstly, considering the analysis of lower limb human structure, the dynamic model of lower limb exoskeleton robot was established. Secondly, the follow-up control model of lower limb exoskeleton robot was established, which based on Iterative Learning Control Algorithm. Finally, the exponential gain close-loop D type motion control system was designed, and the relationship between spectral radius and the convergence speed were analyzed. The hip and knee joints expected trajectory was tracked based on Matlab software. The simulation results show that this algorithm can effectively improve the accuracy of gait trajectory tracking, and the follow-up of human-robot system is promoted.