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.