Acute respiratory distress syndrome (ARDS) is a clinically critical illness characterized by hypoxemia caused by intrapulmonary and (or) extrapulmonary reasons. Its pathogenesis is related to the imbalance of oxidative stress. N-acetylcysteine (NAC) has been widely used in the treatment of respiratory diseases as an antioxidant. At present, there is controversy about whether NAC is beneficial in the treatment of ARDS in terms of antioxidant in China and abroad. This review focuses on the molecular mechanism of NAC, animal experiments and clinical research results, and summarizes the research progress of NAC's antioxidant effect in the treatment of ARDS, in order to provide a reference for the treatment of NAC in ARDS.