Knee pain when squatting mostly refers to knee pain when squatting, and the common causes are ligament injury, meniscus injury, knee degeneration, chondromalacia patellae and so on. 1. Ligament injury: Ligament injury of the knee joint due to jumping down from a high place, walking and falling down, car accident, etc. can cause knee joint instability, pain and other symptoms. 2. Meniscus injury: Meniscus wear and tear due to long-term activities such as hiking, walking up and down stairs, or trauma leading to meniscus injury, increased pressure on the knee joint when squatting, which can cause pain. 3. Knee degeneration: due to old age, obesity, long-distance running and other reasons, resulting in joint cartilage degeneration, osteophytes, squatting when the pressure increases, causing pain. 4. Chondromalacia patella: trauma, excessive exercise and other reasons, causing degenerative changes in the cartilaginous surface of the patella, common symptoms are knee pain, weakness, difficulty in activities. Causes of knee pain when squatting are more reasons, may also be related to osteosarcoma, lumbar disc herniation and other diseases, if the symptoms continue to be unrelieved, it is recommended to consult a doctor in time, to clarify the cause of the disease, targeted treatment.