Abstract: OBJECTIVE To develop an HPLC method for determination of liquiritin, cinnamic acid, cinnamaldehyde and isoliquiritigenin in Guizhi-Gancao decoction with gradient elution and double-wavelength switch. METHODS The analysis was carried out on a Kromasil C₁₈(4.6 mm×250 mm, 5 μm) column. The mobile phase was composed of acetonitrile and 0.1% formic acid aqueous with gradient elution and the flow rate was set at 1.0 mL·min^-1. The detection wavelengths were set at 276 nm for liquiritin, cinnamic acid and cinnamaldehyde (0-29.5 min) and 370 nm for isoliquiritigenin (29.5-32.0 min). The column temperature was 35 ℃. RESULTS The linear ranges of liquiritin, cinnamic acid, cinnamaldehyde and isoliquiritigenin were 10.0-160, 2.50-40.0, 16.0-256, 0.050-0.8 μg·mL^-1, respectively. CONCLUSION This method can be used to determine the above 4 components with satisfied accuracy and repeatability.