The most common causes of knee pain when squatting are meniscus injury, osteoarthritis of the knee, ligament injury and so on. 1. Meniscus injury: if the patient has a history of meniscus injury or injury diagnosis, the pressure on the meniscus becomes greater when squatting, which in turn causes synovial and knee pain. 2. Knee osteoarthritis: due to trauma, inflammation and other factors causing degenerative changes in the knee cartilage and secondary osteophytes, squatting back and forth pressure and stimulation to the cartilage bone, there may be knee pain, squatting in the process of the pressure becomes greater will also produce pain. 3. Ligament injury: if or around the knee ligament strain or rupture, squatting process ligament tension and pressure may increase, pulling to the damaged ligament will produce pain. Caused by squatting knee pain causes more, may also be associated with fractures, prepatellar bursitis and other reasons, if the symptoms continue to have no relief, it is recommended to promptly go to the hospital to find out the cause of the disease, by the doctor targeted treatment.