Objective To observe the efficacy and mechanism of Qingdan Decoction （Gallbladder-Clearing Decoction） com-bined with biliary decompression for acute cholangitis severe type （A CST）.Methods The ACST models were established with laparotomy preparation on 48SD rats.The rat models were randomized into the ACST group

Qingdan Decoction group

de-compression group and Qingdan Decoction+decompression group

with 12in each.Six hours after modeling

the Qingdan De-coction group was given intragastric administration of Qingdan Decoction

the decompression group was given biliary decom-pression and drainage and intragastric administration of saline

and the Qingdan Decoction+decompression group was given bil-iary decompression and drainage and Qingdan Decoction.The tissues were drawn after 48hours.The mortality of rats was cal-culated.The blood count

liver function

lipopolysaccharide （L PS） and tumor necrosis factor-α （TNF-α） was detected.The pathological changes of the liver were observed by light microscope.Results The mortality in the ACST group was the high-est

but with no significant difference between Qingdan Decoction group （P>0.05）.The mortality in the decompression group and Qingdan Decoction+decompression group was significantly lower （P<0.01）.Comparing with the ACST group

the blood count and liver function in the decompression group and Qingdan Decoction+decompression group was significantly improved （P<0.05or P<0.01）.The liver function indicators in the Qingdan Decoction group were significantly higher than those in the decompression group and Qingdan Decoction+decompression group （P<0.01）.Comparing with the ACST group

the lev-els of LPS and TNF-αwere significantly decreased in the other groups （P<0.05or P<0.01）

and the decrease was more sig-nificant in Qingdan Decoction+decompression group than that in the decompression group （P<0.05）.Conclusion Qingdan Decoction combined with biliary decompression can obviously lower the mortality and improve the liver function of rat with ACST.The mechanism might be related with the decrease of the level of serum LPS and TNF-α.