In present study, we conducted quantification analysis of phenolic compound (paeonol), monoterpene glycoside (paeoniflorin), and tannin ((+)-catechin in the 70% ethanol extracts of non-processed Moutan Radicis Cortex (MRC) and processed MRC by roasting using a high-performance liquid chromatography coupled with photodiode array detector. Three marker components were separated on Gemini C18 analytical column and the column was maintained at 40℃ using two mobile phase system consisting of 1.0% (v/v) aqueous acetic acid and 1.0% (v/v) acetic acid in acetonitrile. The flow rate and injection volume were 1.0 mL/min and 10 mL. In non-processed MRC sample, the concentrations of three marker compounds, (+)-catechin, paeoniflorin, and paeonol were 0.20, 1.18, and 2.12%, respectively. On the other hand, the concentrations of the three compounds in processed MRC samples were 0.03-0.24, not detected-1.08, and 0.76 1.82%, respectively.