The knee pain can be caused by the following reasons: first, patellar tendonitis or quadriceps tendonitis, these two diseases can lead to pain above and below the patella after squatting for a long time, then it is necessary to check the MRI of the knee joint and check the body for early diagnosis and treatment. Second, osteoarthritis of the knee joint, severe osteoarthritis of the knee joint can involve the meniscus, soft tissues and cartilage of the knee joint, and there is a large amount of bone superfluous formation, which can have the symptoms of knee pain after squatting for a long time, then we should check the X-ray and CT of the knee joint for diagnosis and treatment. Third, damage to the meniscus of the knee joint, damage to the posterior horn of the meniscus of the knee joint and tears, there can be squatting for a long time after the posterior horn of the meniscus is squeezed, resulting in pain in the knee joint, then you should check the MRI of the meniscus to diagnose and treat.