Objective: To observe the influence of Xiefei Pingchuanling and its decomposed formulas on serum changes of endotoxin (ET) and tumor necrosis factor-α (TNF-α) in model rats with 'interior and exterior relationship between the lung and the large intestine’. Method :Seventy SD rats were randomly divided into 7 groups: the normal group

the model group

the unhitch group

the Sanao group

the Santong group

the Sanhuo group and the Xiefei Pingchuanling group. The rat model of 'interior and exterior relationship between the Lung and the Large intestine’ was established to intestinal obstruction by incomplete ligation of the rectum in vitro. The rats in model group were killed after 3 days. The Sanao group was treated by Sanao decoction with the crude drug dosage of 3.92 g ·kg-1 intragastrically

the Santong group was treated by Santong decoction with the crude drug dosage 7.11 g ·kg-1 intragastrically

the Sanhuo group was teated by Sanhuo decoction with the crude drug dosage 10.54 g ·kg-1 intragastrically

the Xiefei Pingchuanling group was treated by Xiefei Pingchuanling decoction with the crude drug dosage 16.66 g ·kg-1 intragastrically. The rats were killed after 3 days of ig. The changes in serum ET and TNF-α were observed to investigate the interventional effect of Xiefei Pingchuanling and Its decomposed formulas. Result : The serum levels of ET and TNF-α were increased significantly in the model group(P＜0.01). The serum levels of ET and TNF-α were decreased in the other groups compared with the models(P＜0.01). The synergies existed in some groups. Conclusion :Xiefei Pingchuanling and its decomposed formulas can protect the lung tissue

alleviate pathological change and prevent the tissue of the model rats from endotoxemia.