Abstract: The urine sample (1.00 mL) was mixed with 10 μL of 1.0 g·L^-1 α-naphthyl acetate solution for 10 min by vortex. 0.1 mol·L^-1 Copper sulfate solution, 0.5 mL of 0.3 mol·L^-1 naphthylamine solution, 1 mL of 50.0 g·L^-1 HNO₂ solution and 0.1 mL of 1 mol·L^-1 HCl solution were added into the solution, and the mixture was swirled for 3 min. The solution was refrigerated at 4℃ for 10 min, and then heated at 50℃ for 10 min. After centrifugation, the organic phase was separated by GC using DB-5MS capillary column. SRM was adopted in MS. Linear relationship between values of peak area and mass concentration of cyanide ion was found in the range of 0.1-10 mg·L^-1, with detection limit (3S/N) of 0.015 mg·L^-1. Test for recovery was made by standard addition method, giving results in the range of 90.2%-106%, with RSDs (n=6) all less than 3.5%.