Fat embolism syndrome (FES) is a complication of severe injuries such as trauma and fractures. Although it has been a century since Zenker first discovered fat droplets in the pulmonary vascular bed of a fatal case of severe trauma in 1882 and Bergmann first clinically diagnosed fat embolism in 1887, and many people have conducted research from different angles, the clinical manifestations of FES vary greatly. Some cases are fierce and sudden, and even die soon before the typical symptoms appear. Some may have no obvious clinical symptoms and are only discovered after autopsy. Therefore, it was not until the past 20 years that its pathophysiology was further understood. Bagg (1979) et al. believed that this syndrome is post-traumatic respiratory distress syndrome that occurs within 72 hours after fracture trauma. In the early stage of trauma, if there are special signs such as tachycardia, temperature rise above 38°C, arterial oxygen partial pressure (PaO2) decrease, and snowstorm shadows in the lungs, it can be diagnosed. Broder believes that in addition to trauma, burns, metabolic diseases, decompression sickness, connective tissue diseases, severe infections, neoplasms, osteomyelitis, etc. can also induce FES.