”Cold leg”, also known as “osteoarthritis of the knee joint”, is a common disease in the elderly. Osteoarthritis of the knee joint is mainly caused by degenerative changes in the articular cartilage for some reasons, followed by relaxation of the joint and surrounding ligaments, atrophy or hyperplasia of the synovial membrane, and a decrease or increase in the secretion of synovial fluid, causing inconvenience, swelling and pain in the joint. ”Old cold leg” starts slowly, with vague pain on both sides or one side of the knee joint, which is aggravated when moving, but improves after rest. The symptoms are aggravated when it rains on cloudy days or when the climate becomes cooler, so it is a common feature of patients with this disease that they prefer warmth and fear cold. Sometimes the pain is acute, the joint is stiff, and there is a popping sound when moving. The stiffness of the joints worsens after prolonged sitting and improves slightly after activity. In the late stage, the joints become swollen, restricted in movement and even deformed. In autumn and winter, as the weather becomes cooler, “old cold leg” will recur and needs special protection. Firstly, we should improve the health quality of the whole body, especially in middle age, we should pay attention to the regularity of life, prevent trauma or overwork, moderate diet, prevent excessive obesity, in order to reduce the weight of the joints. Secondly, we should pay attention to the health care of the knee joint, pay attention to the warmth and cold of the knee joint, prevent the joint from being attacked by cold and damp, and use knee pads. Third, reasonable physical exercise is necessary to promote the absorption of nutrients into the joint cartilage and to maintain the range of motion of the joint. At the same time, it is important to combine work and rest to avoid too much activity and damage to the joints. Four “old cold leg” relapse must be timely to the regular hospital pain specialist, joint internal and external joint treatment, interrupt the vicious circle of disease development, prevent the development of disease and early recovery.