Abstract： Objective To investigate the effects of clara cell secretory protein (CC16) and secretory phospholipase A2 (sPLA2) on ventilator induced lung injury (VILI) by observing their expressing in lungs of rats with different tidal volume ventilation.Methods 24 health Wistar rats were divided into three groups:control group,low tidal volume group and high tidal volume group.The total protein (TP)and polymorphonuclear cells (PMN) in bronchoalveolar lavage fluid (BALF) were measured.The expression of sPLA2 mRNA in lung tissues was detected by reverse transcription polymerase chain reaction (RT-PCR).The number of Clara cells and the expression of CC16 in lung tissues were detected by immunohistochemistry.Results The level of TP and PMN in BALF and the expression of sPLA2 mRNA in lung tissues in control and low tidal volume groups were increased significantly than that in high tidal volume group ( P ＜0.01).The number of Clara cells and the expression of CC16 in lung tissues in control and low tidal volume groups were decreased significantly than that in high tidal volume group ( P ＜0.01).There were no statistic differences existed between the low tidal volume group and control group (P ＞0.05).Conclusions Over expression of sPLA2 mRNA induced by high tidal volume ventilation caused Clara cells decreasing and CC16 low expressing which lead to lung tissue inflammation aggravated may be one of the important factors giving rise to VILI.