Hemothorax is mainly caused by two conditions, one is called spontaneous hemopneumothorax, and most of the spontaneous hemopneumothorax is caused by the rupture of pulmonary blisters, after the pulmonary blisters are broken and the lung is atrophied, the lung drops down under the effect of gravity. Many patients with pulmonary herpes have vascular adhesions on the lung tip, which tear under gravity and break the bundle after tearing, thus causing bleeding. Because the blood is circulating in the body and the pressure is high, self-healing is less likely and bleeding tends to persist. The other kind is caused by trauma, the most common one is a car accident that breaks the ribs, resulting in bleeding from the stump, the blood from the stump is relatively small, if the external force is not very large, the fracture dislocation is not serious, the bleeding from the stump will be less, if the dislocation is serious, it will puncture the lung, and the lung will bleed. The bleeding of the lung is because it is the blood of the pulmonary circulation, which will slowly stop by itself after the lung is atrophied. After the rib is broken, the intercostal artery and vein are damaged, and the pressure of the body circulation is relatively high, so it is difficult to heal by itself, and in many cases, surgical treatment is required. Therefore, the treatment of hemothorax depends not only on the degree of injury, but also on the amount of bleeding. Patients with more bleeding should be operated, while patients with less bleeding can be treated by placing a drain.