Based on the positional characteristic of ellipticorbit of four-bar linkage, we develop a device to support rehabilitation of a patient’s lower limb’s motion in two-dimensional plane. In addition, we use ADAMS software to analyze two aspects parameters. One aspect is about the horizontal and vertical displacement of four-bar mechanism of ellipticorbit. The other simulation is about angles θ1 (angle between thigh and the horizontal) and θ2 (angle between thigh and calf). Before using the device, we install them in both sides of a normal chair. Driven by electric motor, lower limbs can follow the trajectory to do rehabilitation exercise. Long-term exercise can help a patient to repair damaged muscles.