A simple, accurate and reliable method for the simultaneous separation and determination of 9 active components (danshensu, protocatechuic acid, protocatechuic aldehyde, caffeic acid, rosmarinic acid, salvianolic acid B, paeonol, paeoniflorin and gallic acid) in traditional Chinese medicinal preparation ShuangDan (SD) oral liquid was developed using reverse phase high-performance liquid chromatography (RP-HPLC) coupled with photodiode array (PDA) detection. The chromatographic separation was performed on a SinoChrom ODS-BP C18 column with gradient elution using methanol (A) and 3% glacial acetic acid aqueous solution (B) at a flow rate of 1.0 mL min−1, and with a PDA detection. Good linear behaviors over the investigated concentration ranges were observed with the values of r2 higher than 0.9992 for all the analytes. The recoveries and relative standard deviation (RSD), measured at three concentration levels, varied from 98.21% to 101.82% and 0.07% to 1.37%, respectively. The proposed method enables the simultaneous identification and determination of 9 active components in a single run for the quality control of ShuangDan oral liquid.