Background Serious infection, shock and other factors will result in an acute lung injury, which is considerd due to excess and runaway inflammatory reaction.It could increase the incidence of complications and mortality rate, and influent the prognosis. Dexmedetomidine has satisfactory sedative and analgesic properties. Several trials have proved its advantages on anti-inflammatory and organ Protective Effects. Objective Our current article reviewed the protective effects and mechanism of dexmedetomidine on lung injury. Content This article described the pharmacological characteristics of dexmedetomidine, the mechanisms of several kinds of lung injury, and protective effects and mechanism of dexmedetomidine on lung injury. Trend Dexmedetomidine can effectively prevent lung injury. However, this effect is mainly found in animal trials. There are few reports on clinical trials. Further studies are wanted to evalauate its clinical effectiveness,in order to expand its clinical application．