Abstract: After seawater drowning, except for larynx and trachea reflex spasm causing acute asphyxia, the main cause of death is pulmonary edema of seawater drowning. The mechanisms of pulmonary edema after seawater drowning include the hyperosmolality of seawater, the liquid malabsorption in alveolus,the effects of inflammatory mediators,reactive oxygen species and neurohumoral factors.