Running knee pain is considered to be caused by incorrect posture, meniscus injury and synovitis. 1. Incorrect posture: If the posture is not standardized when running, the force on the knee is not uniform, which will cause greater wear and tear and lead to knee pain when running. 2. Meniscus injury: during running, the knee joint will be overloaded and squeezed, and it will also lead to knee flexion and extension activities, which will lead to the friction of the knee joint, resulting in obvious knee pain. 3. Synovitis: knee pain after running may be due to excessive friction of the cartilage between the patella and the femur, resulting in cartilage wear and tear, and synovial inflammation at the same time, joint pain will occur. Patients with symptoms of running knee pain should promptly go to the hospital under the guidance and advice of the doctor for X-rays, or even CT MRI, to clarify the cause of knee pain and correct treatment.