This paper describes a kinematic model of Support robot for elder people. This support robot can help elders who do not have enough physical strength on the lower limbs during sit to stand due to aging. It also follows the natural pattern of human motion during sit to stand. Several experiments were carried out using optotrack to measure the human motion posture while sit to stand motion in addition to estimate the required trajectory for support robot during assisting. Computer program was developed to evaluate the variables of the support robot with the sit to stand trajectory.