Objective To compare the effects of high frequency oscillatory ventilation (HFOV) and conventional mechanical ventilation (CMV) whith or without pulmonary surfactant(PS) supplement on water vapour inhalation injury.Methods New Zealand rabbits model of severe acute lung injury with acute respiratory failure caused by steam inhalation was established.Then the animals were treated by CMV，HFOV，CMV+PS or HFOV+PS，respectively while animals in control group did not ventilated and supplemented with PS.Femoral arterial blood samples were obtained at 1，2，3，4 h after treatment for blood gas analysis.4 h after treatment ,the lowest lobe of right lung was weighed for calculating wet-to-dry weight ratio (W/D).Four different parts including dependent areas and non-dependent areas of the middle lobe of right lung were excised for histological observation.Results (A) After ALI established PaO2 in the five groups decreased below 60mmHg (Plt;0.01) but intergroup differences were found.Meanwhile the change of PaCO2 showd no statistical significance(Pgt;0.05).(B) PaO2 in the four treatment groups had increased since one hour after treatmentand sustained at favorite levels during treatment period.PaO2 in the HFOV and HFOV+PS groups were higher than those in CMV and CMV+PS groups,respectively (Plt;0.01，Plt;0.05).PaO2 in the CMV+PS group at 2 h and HFOV+PS group at 2 h and 3 h were significantly higher than those in corresponding non-PS groups at the same timepoints (Plt;0.05).P（A-a）O2 in the HFOV and HFOV+PS groups were lower than those in CMV and CMV+PS groups (Plt;0.05).P（A-a）O2 in the two groups with PS at 2 h，3 h and 4 h t were statistically lower than those in the two corresponding groups without PS (Plt;0.05).The pH and PaCO2 as well as circulatory function in the four groups were not significantly different at different treatment timepoints (Pgt;0.05).(C) Lung W/D was not different between CMV and HFOV groups (Pgt;0.05)，or CMV+PS and HFOV+PS.But lung W/D in the two groups treated with PS showed statistically decrement than that in non-PS groups (Plt;0.05).(D) Histological injury score was lowest in HFOV+PS group and highest in CMV group.Conclusion HFOV combined with exogenous PS supplement can improve arterial oxygenation and alleviate pulmonary edema and injury，which may be a optimal method for the treatment of acute lung injury with acute respiratory failure caused by water vapour inhalation.