Edema is graded into mild, moderate and severe. The edema below the ankle is called mild edema; the edema below the knee is called moderate edema; if the edema has reached the root of the thigh or is accompanied by pleural or abdominal effusion, it is severe edema. The above method of grading edema is relatively well understood and memorized, using the ankle joint, knee joint and the root of the thigh as the boundaries to classify edema into mild, moderate and severe. The severity of edema indicates the severity of the disease, because more severe edema not only manifests itself as generalized swelling, but also causes more serious heart failure, and patients will show chest tightness, breath-holding and difficulty in breathing, and some patients will also show cerebral edema, headache and loss of consciousness. Therefore, after patients develop edema, while giving diuretics to reduce swelling, we should actively search for the cause of the disease and deal with it from the etiology.