Abstract: OBJECTIVE The pharmacokinetic parameters of berberine in rat plasma were studied after oral administration to the monomer of drug-pair of Rhizoma Coptidis-Radix Aucklandiae and explored the pharmacokinetics effect on berberine in rat plasma after oral administration to drug-pair. METHODS The HPLC method was used to determine the quantity of berberine in rat plasma. The Diamonsil C18(150 mm×4.6 mm，5 μm)column was used, the mobile phase consisted of acetonitrile and water (42∶58), including 0.34 g Potassium dihydrogen phosphate and 0.17 g Sodium dodecyl sulfate per 100 mL, the flow rate was 1.0 mL·min-1, the UV detector was operated at 349 nm and the column temperature was controlled at 35℃. RESULTS Pharmacokinetic parameters of the extract of drug-pair: MRT(0-24)(12.470±1.538)h，MRT(0→∞) (29.711±7.176)h，AUC(0→24) (17.797±7.956) mg·L-1·h-1，AUC(0→∞)(92.522±53.784) mg·L-1·h-1，Tmax 2 h，Cmax(1.360±0.042) mg·L-1. CONCLUSION Drug-pair of Rhizoma Coptidis-Radix Aucklandiae is one-compartment model.