If the pleural effusion is caused by trauma, pleural inflammation, hypoproteinemia or cardiac failure, after active treatment and correction of the cause, the pleural effusion can disappear completely and generally will not have any effect on the survival time of the patient. If malignant pleural effusion is caused by malignant tumor invasion of pleura or obstruction of lymphatic flow in the lung, it often indicates that the disease is in an advanced stage of malignant tumor, and most of them have poor prognosis, and the survival time of patients is about 1-2 years.