Pleural effusion can mostly be diagnosed clearly based on the patient’s medical history, physical examination, CT, chest X-ray and other examinations. If the diagnosis is still difficult, physical and chemical examination of pleural effusion by thoracentesis is feasible, and most of them can be clearly diagnosed. The treatment cost of pleural effusion can be divided into the cost of symptomatic treatment and allopathic treatment. The cost of symptomatic treatment is the cost of so-called thoracentesis or closed drainage of the chest cavity. The cost of each thoracentesis and aspiration is about $200, and the cost of closed chest drainage is about $500 each time. The fundamental treatment of pleural effusion lies in the treatment of the primary disease, whether it is an exudative pleural effusion or a leaky pleural effusion. Common causes of leaking pleural effusion are seen in conditions such as hypoproteinemia and cardiac insufficiency. Common causes of exudative pleural effusion include infection, tuberculosis, tumors, and systemic lupus erythematosus. The cost of treatment for the etiology depends mainly on the cause and the effectiveness of the treatment. The cost of these treatments for the etiology is uncertain. In conclusion, there are many causes that can cause pleural effusion, and the cost of each symptomatic treatment is relatively fixed, while the effect of treatment against the etiology is uncertain and the cost is also uncertain.