Abstract: The sample of cucumber was extracted with a mixture of HCl-C2H5OH(5+95), and the extract obtained was separated by centrifugation and purified by passing through activated carbon column. The purified ethephon in the solution after filtration was derivatized with diazomethane, and the derivatized product was used for GC analysis. HP-1701 capillary column (0.32 mm×30 m, 0.25 μm) was used for separation and flame photometric detector was adopted in the determination. Linear relationship between values of peak area and mass concentration of ethephon was obtained in the range of 0.100-2.50 mg·L-1. The proposed method was applied to the determination of ethylene in cucumber, giving average recovery of 97.3% and RSD (n=5) of 4.5%.