Objective To investigate the formulation of ankle rehabilitations motion trajectory by studying the effects of different trajectories of 3-PH/R ankle rehabilitation robot on joints and muscles. Method The 3-PH/R ankle rehabilitation robot is simplified and imported into Anybody by analyzing the kinematics principles. Using the actual motion trajectory of ankle rehabilitation robot as model driving. The changes of joints and muscles were compared under the three different trajectories of dorsiflexion/plantarflexion, inversion/eversion, and nutation. And analysis of the relationship among the three motion trajectory through correlation. Results Nutation can satisfy the function of both plantar dorsiflexion/plantarflexion, and inversion/eversion, and make the ankle muscles fully exercise. There is no significant difference in joint force under three different rehabilitation trajectories, with a maximum difference of 0.3N. Different muscles have different sensitivity to trajectories. Conclusions In this paper, a continuous dynamic analysis of muscle force and joint force under three kinds of rehabilitation trajectories is implemented. The results have certain theoretical significance and clinical reference value for the clinical application of ankle rehabilitation robot and the formulation of rehabilitation trajectory.