Abstract: The collected water sample was directly placed into a 22 mL-headspace vial and filled it up to the 10 mL mark. 200 μL of methanol as preservative was added, and the solution was sealed immediately, and stored in the dark at 4 ℃. The analysis should be completed within 48 h. Tetraethyl lead in water samples was equiliphated at 60 ℃ for 15 min in a weakly alkaline or alkaline environment, then simultaneously entered two chromatographic columns through the Y-shaped manifold of the gas chromatograph and detected by dual electron capture detectors（ECD）. Two sets of data were obtained. Only when tetraethyl lead was detected by dual ECD, it would be judged as a positive result, and the lower detection results would be taken as the content of tetraethyl lead in the water sample. As shown by the results, linear relationships between the peak areas detected by the corresponding dual columns and dual ECD and mass concentration of tetraethyl lead were kept in the range of 0.1−10.0 μg·L⁻¹, with detection limits （3.143s） of 0.009 μg·L⁻¹ and 0.013 μg·L⁻¹, respectively. Test for recovery was made on blank water samples by the standard addition method, giving results in the range of 94.3%−120%, with RSDs （n=7） of the determined values less than 5.0%.