Generally speaking, squatting knee pain is an abnormal situation, and it is recommended that patients should go to regular hospitals for examination first, which is usually due to the damage of internal tissues of the knee joint, knee cartilage injury, meniscus injury, synovitis and so on. 1. Cartilage injury: it can occur in various joints, and the most vulnerable joints among athletes are knee joint (especially patellofemoral joint), ankle joint and elbow joint; common symptoms include joint pain, joint swelling and activity limitation. Knee pain occurs when squatting because the damaged cartilage surface rubs against each other when the joint moves, causing pain. 2. Meniscus injury: knee pain is a common symptom, when the posterior horn of the meniscus injury or meniscus tear, can cause knee pain symptoms when squatting, due to the injury site is squeezed, or torn meniscus into the intercondylar fossa caused by joint interlock. 3. Synovitis: the cause of the disease is relatively more diverse, excessive joint movement, joint injury, cartilage degeneration and osteophytes and other reasons can lead to the occurrence of synovitis, some patients with synovitis may also be related to infection. It is usually characterized by swelling and pain in the knee joint, and if the disease continues to progress, it can lead to joint adhesions and limited knee movement. There may also be other factors causing the disease, as this symptom alone is not enough to diagnose the disease. Therefore, it is recommended that if physiological causes are ruled out, timely consultation should be made, so that the doctor can clarify the cause of the disease and give targeted treatment.