Whether joint effusion can heal by itself is as follows: a. It can heal by itself: when a small amount of joint effusion occurs in patients, it can be absorbed by itself. Generally, we should take more rest, avoid excessive weight-bearing walking and excessive sports, so that synovial inflammation will gradually subside. After the synovial inflammation subsides, the synovial secretion of joint fluid will be reduced and the joint fluid will be absorbed on its own. Second, it is difficult to heal by itself: if there is a large amount of fluid in the joint, the joint swelling is obvious, and the physical examination is clear that the floating patella test is positive, it is difficult for the joint fluid to be absorbed by itself at this time. Generally in this case, the patient has to undergo joint cavity aspiration treatment, and the joint fluid has to be extracted to make the joint swelling subside, and the knee joint has to be wrapped with an elastic bandage after the extraction, which can prevent the recurrence of joint effusion.