A large amount of fluid in the knee joint can be treated with general therapy, medication, functional exercise and arthrocentesis according to the cause of the disease. 1. General treatment: pay attention to the warmth of the knee joint, avoid cold, reduce the activities of the knee joint, which can help to reduce the local exudation and accelerate the absorption of the effusion. 2. Medication: For pain and discomfort caused by large amount of fluid in the knee joint, oral anti-inflammatory and analgesic medications such as ibuprofen and celecoxib can be taken under the guidance of specialized doctors, and synovitis tablets can also be applied for treatment. 3. Functional exercise: more bed rest is needed, straight leg raising training can be performed under the guidance of the doctor, each time about 50 times, 3-5 times a day, in order not to cause discomfort. Functional exercise can increase the pressure in the joint cavity, reduce synovial leakage, and prevent joint stiffness and muscle atrophy. 4. Arthrocentesis: When the conservative effect is poor and the joint cavity is inflamed with fluid, arthrocentesis can be performed in regular hospitals to extract the fluid, which can help to relieve the local swelling, reduce the pain symptoms, and improve the mobility of the knee joint. If the joint effusion is caused by synovial lesion of knee joint, arthroscopic surgery can be performed to remove the synovial lesion if necessary. If the joint effusion is caused by rheumatoid, gout, tuberculosis and other diseases, it can be treated by applying anti-rheumatic drugs such as methotrexate and leflunomide, uric acid-lowering drugs such as febuxostat and allopurinol as well as anti-tuberculosis drugs such as isoniazid and rifampicin under the guidance of doctors. When a large amount of fluid accumulates in the knee joint, one should consult a doctor in a timely manner, and under the guidance of a specialized doctor, actively carry out appropriate treatment, which will help to alleviate the uncomfortable symptoms as soon as possible.