Abstract: ［Abstract］Objective　To study the characteristics of liver injury induced by simvastatin combined with HRZ （ Isoniazid， Rifampicin and Pyrazinamide ） in SD rats. Methods　Fifty-four 8-week-old SD rats were randomly divided into 3 groups: group A（ control ）， group B （ HRZ ） and group C （ simvastatin combined to HRZ ）， half of each group were male. We calculated the accurate dose respectively before those rats were given intragastrical administration of corresponding drugs. Six rats were killed in each group on 10th ， 20th and 40th day， respectively. Before this， blood was fastened from femoral of every rat that would be killed to test liver function， liver tissue slices were made in order to observe the pathological characteristic. Results　Alanine amiotransferase of group C elevated in line with time and reached statistic difference on 40th day， furthermore， it was significantly higher than group A（ P＜0.05）. Total bilirubin and direct Bilirubin of group C were significantly higher than those of group A from the beginning to the end（P＜0.05）， however， they declined rapidly on 10th day， this trend also had statistic difference（P＜0.05）. At the end of this experiment， hepatic cords was disordered slightly，but swelling liver cells and vacuolar degeneration were observed， the nuleus of cell condensed. Soakage of monocytes， neutrophils， and lymphocytes occurred in the portal and lobule regions，or even spotty necrosis occasionally. Conclusion Cholestasis occurs at the early stage when simvastatin is combined with HRZ in SD rats，however，it has a rapidly degressive trend. In contrast，Alanine amiotransferase elevates，furthermore，pathological injury or even spotty necrosis can emerge in liver tissue slices.