Object To develop a new method for the quantitative determination of spinosin in the seed of Ziziphus jujuba Mill. var. spinosa (Bunge) Hu ex H. F. Chou Methods The determination was carried on RP-HPLC, using Hypersil-C 18 column, acetonitrile∶water (17∶83, v/v) as mobile phase with a flow rate of 0 8 mL/min and detected at the wave length of 334 nm Results The calibration curve was linear in the range of 5 280～ 14 08 ?g/mL The average recovery rate was 95 8% Conclusion The method is appropriate for the quantitative determination of spinosin