Abstract: (±)-Praeruptorin A(PA)was used as the standard reference substance to establish a new method of substitute for reference substance. The contents of both(±)-praeruptorin B(PB)and(+)-praeruptorin E(PE)were calculated by the method. The major content of coumarins in different processing materials could be gained by determining the content of(±)-praeruptorin A, which could provide scientific evidence for the research on pharmacology discrepancy and quality standards. The method was carried out on a Welch Materials Ultimate XB-C₁₈ column(4. 6 mm×250 mm, 5 μm), with a gradient mobile phase of methanol and water at the flow rate of 1. 0 mL/min. The column temperature was 30 °C and detection wavelength was set at 322 nm. According to this method, the relative correlation factors(f)of(±)-praeruptorin B and(+)-praeruptorin E were determined as 0. 787 2 and 0. 969 0, respectively. After determine the contents of 15 batches of materials from different sources, no significant differences between substitute method and external standard method were observed. It was a feasible and credible method to determine the content of major coumarins in Peucedani Radix with different processing materials. The results showed lower contents of coumarins in processing materials than in raw materials.