In everyday activities, the injuries to lower limb are considered to rehabilitate in urgent priority. The rehabilitation is to restore the patient's physical, sensory, and mental capabilities due to injury, illness, or disease in normal condition. The typical habilitation for lower limb is separated in three types , which ar e active , passiv e and active -assi stive mode. Active mode is one important aspect of rehabilitat ion for increasing or maintaining joint function providing appropriate resistance to the muscles to increase endurance and strength . For passive mode , patients cannot activ ely participate in rehabilitation and no effort is required from them. Patient’s lower limb will be driven by exoskeleton suit. This rehabilitation motion is influenced by bone surfaces within the joint, joint capsule, ligaments, tendons, and muscles acting on the joint. In this paper, the new hardware design is introduced and the possible motions of each joint are simulated. The relative positions of each joint are determined by Denavit- Hartenberg method. In simulation the revolute, speed and acceleration of each joint in left side are studied to construct the real hardware.