OBJECTIVE:To establish a method for the simultaneous determination of costunolide and dehydrocostus lactone in Haoweilai soft capsule. METHODS:HPLC was performed on the column of Dikma C18 with mobile phase of acetonitrile- water (V/V,55∶45) at a flow rate of 1.0 ml/min,detection wavelength was 225 nm,column temperature was 25 ℃,and the injection volume was 10 μl. RESULTS:The linear range were 24.00-108.00 μg/ml(r=0.999 7) for costunolide and 20.88-93.98 μg/ml for dehydrocostus lactone (r=0.999 8);RSDs of precision,stability and reproducibility tests were lower than 1%;recoveries were 98.71%-100.00%(RSD=0.25%,n=6)and 96.88%-99.18%(RSD=0.40%,n=6). CONCLUSIONS:The method is simple with good stability and reproducibility,and can be used for the simultaneous determination of costunolide and dehydrocostus lactone in Haoweilai soft capsule.