Knee pain in the elderly is caused by the following reasons: First, the elderly maintain the same posture for a long time, so that the knee joint is used for too long, resulting in strain on the knee and pain. Second, degenerative changes in the knee joint, such as arthritis, can cause pain in the knee when moving. Third, the cartilage surface of the knee joint may be worn out, leading to synovitis and pain during activities. Fourth, the elderly may have engaged in sports in their lives, due to the degeneration of the body’s functions, the meniscus of the knee joint degenerates, causing damage to the meniscus and resulting in pain in the knee. It is advisable to rest in bed, reduce floor activities and apply heat to the knee every day to relieve the pain.