A portable gait analysis system that can be used in real outpatient clinics, and a gait analysis system that can be used by children. Analyze people's posture during walking, and evaluate walking functions, such as cerebral palsy tipped gait, stroke and hemiplegic gait. Analyze people's abnormal postures, such as scoliosis, XO-shaped legs, etc. It can analyze the way of landing and impulse during running.