Symptoms and performance of malignant pleural effusion mainly depend on the primary disease and the amount of pleural effusion; malignant pleural effusion is caused by malignant tumors invading the pleura, which is common in middle-aged and old-aged people, and there are often symptoms such as dull pain in the chest, coughing up blood sputum and emaciation, etc. It is seen that the pleural effusion is mostly bloody, and the amount is large and grows rapidly. Symptoms are related to the amount of effusion: there are no obvious special symptoms when the effusion is less than 0.3~05L, but palpitation and dyspnea can be obvious when a large amount of effusion is present, which may even lead to respiratory failure; dyspnea is the most common. In small amount of effusion, there may be no obvious signs, and in medium to large amount of effusion, it can be seen that the affected side of the thorax is full, and the breath sounds are reduced or disappeared, which may be accompanied by the trachea, and the mediastinum is shifted to the healthy side. Malignant pleural effusion is mostly a complication of advanced malignant tumors, and the rapid growth of pleural effusion often causes severe respiratory distress and even death due to the pressure of large amount of effusion; there are many treatment modalities, but the prognosis is still poor. This disease is highly specialized, we should go to regular hospitals in time, determine the specific treatment plan under the guidance of doctors, and actively cooperate with the treatment to avoid deterioration of the condition.