The pain in the knee joint when squatting is mainly considered for the following two reasons: 1, posterior horn injury of the knee meniscus, the knee in the process of flexion, especially when squatting too much flexion, will lead to a significant increase in the posterior horn traction force, the torn meniscus will further aggravate the pain caused, magnetic resonance examination can be clear, treatment requires partial meniscectomy. 2, osteoarthritis of the knee joint, mainly for the patella and femur joint surface The pain will be aggravated by the wear and tear of the articular surface and the exfoliation of the articular cartilage. However, with further development, the cartilage is completely stripped and joint replacement surgery is required for complete recovery.