To observe the efficacy of Kangxian Yi’Ai formula on liver precancerous lesions through immunohistochemistry test by gastric administration in rats.Methods：To randomly divide 55 male Wistar rats into four groups： 10 in the normal group， 10 in the model group， 15 in the Fuzheng Huayu capsule group and 15 in the Kangxian Yi’ai formula group respectively. Diethylnitrosamine had been given to induce liver precancerous lesions in all groups except the normal group for 14 weeks， once a week. Meanwhile， besides the normal group， saline， Fuzheng Huayu capsule and Kangxian Yi’ai fomula were also given the same dosage at each time in respective groups. At the end of the 14th week， tissues were taken to test the pathology of the liver， together with the IHC index included GST-Pi， PCNA and FN. Results： The liver HE and Masson staining showed that Kangxian Yi’ai formula could reduce the cirrhosis degree and the size of lesions much obviously than Fuzheng Huayu capsule did. In addition， the Kangxian Yi’Ai formula could reduced the FN， GST-Pi and PCNA much greatly than the control group (P<0.05) and the Fuzheng Huauu group (P<0.01， P<0.01 and P<0.05). Conclusion： Kangxian Yi’ai formula could constrain cirrhosis and the liver precancerous lesions induced by diethylnitrosamine in rats， but its mechanism is yet to be found.