Objective: To explore the changes of cellular apoptosis and expression of Bcl-XL/Bax in lung during total hepatic ischemia-reperfusion (I/R ) in rats ,and the relationship between their changes and lung injury. Methods: Total hepatic I/R was produced by occlusion of hepatic helium for 30 minutes, and the occlusion was then released for reperfusion. 48 healthy male SD rats weighing 250～300g were were killed respectively prior to ischemia and at 0h, 0.5h, 1h, 3h ,6h of reperfusion,and the lung tissue was taken for determation of apoptotic cells , Bcl-XL mRNA,Bax mRNA expression ，wet/dry(W /D) ratio and histological examination. Results: After hepatic I/R the W /D ratio（4.96±0.25，5.30±0.32，5.36±0.32，5.71±0.33 and 5.32±0.28）and apoptotic index （4.86±0.64%，7.64±0.61 %，15.60±0.59 %， 19.74±0.71 % and 27.48±0.88 %）were increased（P＜0.05),compared with preischemia(4.59±0.24 and 4.00±0.45%).And the Bcl-XL/Bax ratio after hepatic I/R (1.01±0.13，0.43±0.03，0.51±0.07，0.62±0.06，0.62±0.07) were decreased（P＜0.01), compared with preischemia(1.48±0.11). Histological examination revealed that the alveolar architecture was destroyed,with interstitial thickening and neutrophil infiltration after hepatic I/R. Correlate analysis revealed that the apoptotic index showed a positive correlation with the W/D ratio（r= 0.56，P＜0.01) and a negative correlation with the Bcl-XL/Bax ratio（r= -0.55，P＜0.01). Conclusion: Total hepatic ischemia-reperfusion in rats could lead to aggravation of pneumocyte apoptosis ，which promoted acute lung injury,and the reduction of Bcl-XL/Bax ratio during this period may mediate the occurrence of apoptosis .