This paper introduces a prototype of a Lower limb rehabilitation exoskeleton (LLRE) designed to help patients exercise their balance ability. The paper establishes the kinematic models of the leg abduction mechanism and the unilateral mechanical leg and analyzes their workspaces. An innovative rehabilitation mode integrating standing balance and trajectory training is designed, and the training effects are demonstrated in human subject experiments. The proposed mode is shown to effectively transfer the patient’s center of gravity and improve the training effect, promising to enrich the rehabilitation mode of exoskeleton robots.