To observe the effects of Yinchenhao decoction on endoplasmic reticulum stress caspase-12 pathway of cholestasis liver fibrosis rat and its action mechanism on anti bile siltation liver fiber.Methods:Thirty five SD rats were divided into sham operation group and the duplicate model group. The common bile duct ligation method was used to replicate cholestasis liver fibrosis in rats. After 1 week of building, the rats were divided into model group and TCM group. TCM group was given3.5 g/kg Yinchenhao decoction by intragastric administration. The rats were killed after four weeks. HE and Masson staining method were used to observe the changes of the liver tissue pathology, and Western blot method was used to detect GRP78, eIF2 alpha and Caspase-12 protein expression changes in liver tissue of each group.Results:The liver histopathology examination showed that the liver fibrosis rat model was duplicated successfully. The degree of liver fibrosis in the TCM group was lower than that of the model group (P<0.05), but it was more severe than that of the Sham operation group. Blot Western showed that the expression of Caspase-12, eIF2α and GRP78 in the model group was significantly higher than those of the Sham operation group (P<0.01). Besides, eIF2α and Caspase-12 significantly decreased in the TCM group (P<0.01).Conclusion:Inhibiting eIF2α and caspase-12 activation, reducing apoptosis of liver cells, thereby inhibiting the promoting effect of ERS in the liver fibrosis of bile stasis is one possible action mechanism of Yinchenhao decoction in removing bile stasis liver fibrosis.