To establish a quantitative method determination of swertianolin in Gentianopsis paludosa(Munro) Ma by RP-HPLC.The sample were separated on the column of Kromasil-C18(4.6mm×250mm,5μm) which eluted with 55% methanol and water(containing 0.04% phosphoric acid) with detected wavelength at 254 nm.The flow rate was 0.8 mL·min-1,and the column temperature was 30 ℃.The components were base-isolated.The linear ranges of swertianolin was 0.275-1.65μg(r=0.9997).The average recovery rate was 99.6%(RSD=2.7%).The method is rapid and precise.