Pulmonary embolism refers to a group of clinical syndromes in which the pulmonary arteries and their branches, due to the blockage of emboli, cause obstruction of pulmonary circulation. It includes thromboembolism, fat embolism, amniotic fluid embolism, air embolism and so on. Generally speaking, the condition is more critical, but as long as the rescue is timely, it can be cured. 1, the cause of 1, thromboembolism: clinically most of the pulmonary artery thrombus embolism from the lower limb deep vein thrombosis, especially from the upper popliteal vein to the iliac vein section of the lower limb proximal deep vein thrombosis; and the upper vena cava thrombosis caused by intravenous placement, intravenous input of irritating drugs, etc.; and atrial fibrillation leading to the formation of the right atrial appendage thrombus; these thrombi can cause pulmonary artery thromboembolism 2.Fat embolism: it is common when long bone fracture or fatty tissue is severely squeezed, which makes fat droplets in the circulating blood flow reach the lungs with blood and finally block the small blood vessels in the lungs; 3.Amniotic fluid embolism: it is mostly seen when amniotic fluid enters the maternal blood circulation during labor and delivery and reaches the lungs causing acute pulmonary embolism; 4.Air embolism: it is mainly caused by the air gathered in the abdominal cavity during maternity surgery Through the open venous sinus into the vein, with the blood circulation to block the small pulmonary vessels, causing pulmonary embolism; also can be seen in chest trauma air into the blood vessels, improper medical operation and divers in deep water rapid rise nitrogen release caused by air embolism. Second, the treatment of pulmonary embolism mainly requires early diagnosis, early intervention, respiratory and circulatory support therapy, anticoagulation therapy and thrombolytic therapy according to the risk level of the patient; although pulmonary embolism is very dangerous, some patients can be cured if they can be diagnosed in time and treated actively at an early stage.