Knee joint injection of sodium vitreous acid, also known as sodium hyaluronate, can be completely metabolized in the body, with good biocompatibility and few adverse reactions, but three side effects can occur with the injection. They are as follows: 1) pain and swelling at the injection site or joint cavity; 2) allergic reactions, such as fever, rash, and headache; 3) joint cavity infection due to lax aseptic operation. Several of the above side effects can be avoided by improving injection techniques and strict aseptic operation. Patients with allergies or those with low immunity should choose injections carefully. By these methods, the occurrence of adverse reactions in patients can be avoided. In case of allergic reactions, fever, headache and rash, no special treatment is needed and the symptoms will disappear on their own after 2-3 days.