After surgery for esophageal cancer, there is little exudation from left lung and little pleural effusion on both sides, which are mostly considered to be caused by hypoproteinemia, recurrence and metastasis of esophageal cancer, and lung infection. 1. Hypoproteinemia: patients with esophageal cancer may suffer from malnutrition due to difficulty in swallowing and eating before surgery, and after surgery, such as with chemotherapy and other treatments, which may also affect eating, many factors may cause patients to suffer from hypoproteinemia, which may lead to pleural effusion. 2. Recurrence of esophageal cancer: If esophageal cancer recurs and metastasizes to lungs and pleura, carcinomatous hydrothorax may appear, which is manifested as exudation from left lung and pleural effusion on both sides. 3. Lung infection: if lung infectious disease occurs after surgery, pleural fluid and little exudation from left lung can also appear under the stimulation of inflammation. There are other causes for the little exudation from left lung and little pleural effusion on both sides after esophageal cancer surgery, so it is suggested that patients should seek medical treatment in time to avoid delaying the condition.