Abstract: OBJECTIVE To obtain a single active recombinant human CYP1A2, in order to take further study of drug metabolism. METHODS The full human CYP1A2 gene was got by RT-PCR from the total RNA being isolated from the human liver. This gene was subcloned into the expression vector pFastBac. Through transposition, recombinant bacmid-CYP1A2 DNA was formed and was then transfected into Spodoptera frugiperda 9 (Sf9) insect cells to generate the target protein with cytochrome P450 reductase (CYPOR). Western Blot analysis was used to identify the expression of CYP1A2, and the enzyme activity was assayed by HPLC with phenacetin as substrate. RESULTS The expression of recombinant human CYP1A2 was detected by Western Blot analysis, and the Km, Vmax and Clint with phenacetin as substrate were (82.04±11.39)μmol·L-1 (n=3), (1.78±0.26)nmol·min-1·mg-1 protein (n=3) and 0.02 mL·min-1·mg-1 protein respectively. CONCLUSION Active human recombinant CYP1A2 was obtained with baculovirus/insect cells expression system and it can be used to study phase I metabolism of other substrates.