Abstract： Objective To investigate the anti-inflammatory roles of ambroxol in rats' gastric aspiration lung injury.Methods Fifty-four Sprague-Dawley rats were randomly divided into three equal groups:control group,iniury group and ambroxol group.Arterial partial pressure of oxygen (PaO2),wetto-dry weight ratio (W/D) of lung,the activity of myeloperoxidase (MPO) were measured.Tumor necrosis factor-α (TNF-α) of serum were examined by enzyme linked immunosorbent assay.Pre-B-cell colony-enhancing factor (PBEF) was examined by Western blot.Lung pathological change was observed by microscope.Results Compared with control group,PaO2 decreased but W/D of lung,the activity of MPO,TNF-α of serum and PBEF expression in injury group increased (all P ＜0.05).Compared with injury group,PaO2 increased but W/D of lung,the activity of MPO,TNF-α of serum and PBEF expression in ambroxol group decreased (all P ＜0.05).The microscopic structure of the control group was normal and the pathological changes of ambroxol group were milder than those of injury group.Conclusions Ambroxol has anti-inflammatory effects by restraining the activity of PBEF and the releasing of inflammatory cytokines on gastric aspiration lung injury.