Abstract: Based on the analysis on the mechanisms of existing robots for ankle rehabilitation,a novel 2-RRR/UPRR par-allel manipulator mechanism that can perform three rotations around the remote centre is presented.It meets the requirements of ankle rehabilitation motions for eversion/inversion,dorsiflexion/plantarflexion,adduction/abduction.The principles that the mechanism can always perform the above motions in its workspace are analyzed based on kinematic pair screw theory in the form of vector,the mobility of the mechanism is calculated,and the rationality of selecting 3 rotation pairs connecting with fixed platform as inputs is discussed.The forward and inverse kinematics of the mechanism are given based on spherical trigonometry,and some numerical examples are presented.The workspace of the parallel mechanism is big enough for ankle rehabilitation.