A gait analysis system includes a foot sensing unit, a knee sensing unit and a portable device. The foot sensing unit measures foot pressure. The knee sensing unit measures the first and the second three dimensional rotational attributes of a knee. The portable device generates ground reaction force direction and knee moment. The ground reaction force direction is determined according to the pressure and the first and the second three dimensional rotational attributes from the knee sensing units and a model of ground reaction force direction. The knee moment is derived by the pressure, the first and the second three dimensional rotational attributes, the ground reaction force direction, the length of tibia and a knee moment model. The gait analysis system recognizes gait information by a gait model and the information gathered from the sensing units, including the pressure on foot and one of the three dimensional rotational attributes. Furthermore, the gait analysis system proposes posture correction advices according to the gait information, the knee moment and the gait model.一種步態分析系統包含足部感測單元、膝部感測單元與可攜式裝置。足部感測單元用以感測壓力資訊。膝部感測單元用以感測第一與第二膝部三維角度資訊。可攜式裝置用以根據壓力資訊、第一與第二膝部三維角度資訊與反作用力方向模型產生反作用力方向資訊，根據壓力資訊、第一與第二膝部三維角度資訊、反作用力方向資訊、脛骨長度與膝關節力矩模型產生膝關節力矩，根據壓力資訊、第一與第二膝部三維角度資訊其中一者以及步態模型決定步態資訊，根據步態資訊、膝關節力矩與步態模型產生步態分析結果。
