Abstract: CYP3A sub-enzymes participate in biotransformation of 45%-60% of commonly used drugs, and play an important role in regulating the interaction of body and external environment and maintaining homeostasis. In order to study the activity of hepatic CYP3A sub-enzymes, the hepatic microsome was prepared by the Ca^2＋ precipitation method, and the activities of CYP3A sub-enzyme was preliminarily studied by using biochemical methods. The result showed that the protein content of hepatic microsome was （1.541±0.264） mg/mL, the content of total CYP was （0.412±0.063 ） nmol/mg, and the activity of erythromycin-N- demethylase was （1.159±0.001） nmol/（mg· min ）, respectively. The results laid a good foundation for further research of metabolic activity of CYP3A subfamily in vitro by using probe drug detection.