The pain in both knees at the same time can be caused by the following reasons: First, gout, which can involve the large joints of the body and lead to bilateral knee pain, which can be accompanied by swelling of the knee joints and joint effusion, and in severe cases, there can be gout stones around the knee joints. Second, rheumatic and rheumatoid diseases, these two diseases can have bilateral symmetrical onset of the knee joint, can have wandering pain, can be accompanied by morning stiffness, then the blood rheumatic series and X-ray of the knee joint should be checked to diagnose. Third, osteoarthritis of the knee joint, osteoarthritis of the knee joint can have simultaneous onset on both knees, which can lead to joint pain, joint deformity and limited joint movement, and in this case, X-rays and CT of the knee joint should be examined for diagnosis and early treatment.