Abstract: To simultaneous determination of synthetic capsaicin (SC) and Tween 20 in SC-sprays for police use, a HPLC-UV-ELSD method was developed. The SC and Tween 20 were successively detected by the UV detector and ELSD detector combined in one HPLC system. The chromatographic conditions were optimized as follow:the mobile phase was methanol and water (80:20), flow rate was 1.0 mL/min, UV wavelength was 280 nm, and the column temperature was set at 28℃. The flow rate of air of ELSD was maintained at 2.5, the pressure was 0.5 MPa, and the temperature of tube was kept at 60℃. The calibration curves built with the mixing standard were linear in the ranges of 196~980 μg/mL for SC,and 212~1 060 μg/mL (R²>0.999) for Tween 20. Results show that, the recoveries can be obtained in the range of 90%~110%. This developed method has been demonstrated to be suitable for determining the real filling agents in SC-sprays for police use.