There are several reasons for the pain in the knee: first, rheumatism and rheumatoid diseases, if long-term work and life in a cold, wet environment, the knee will be attacked by wind and cold and joint pain, then the relevant examination and laboratory tests to confirm the diagnosis, while taking oral anti-rheumatic drugs to treat. Second, arthritis, if the elderly degenerative arthritis or acute arthritis due to cold, then there will be obvious joint pain, pain is usually very obvious when walking for a long time or strain, cold, to take X-rays for examination and treatment. Third, synovitis, synovitis is an acute or chronic inflammation of the synovial membrane of the knee, often with joint effusion, and can be aggravated by cold, resulting in painful symptoms in the knee.