Abstract: Two-dimensional GC (2DGC) was applied to the determination of 6 components in air after TNT explosion. Chromatographic columns of 5A and Porapark Q (3 m×2 mm, 0.18-0.25 mm for both columns) were chosen for determination of CO, CH₄, H₂, N₂ and O₂ with the former column and for determination of CO₂ with the latter one. To overcome the interference of baseline fluctuation, a gas resistance was set in front of the detector, and a gas capacitance was placed at the outlet of sample introducer. By using the gas resistance No.10, the amplitude of baseline fluctuation was lowered to 100 μV with stablizing time of 10 s, and by the combined effect of gas resistance and gas capacitance, baseline fluctuations due to valve switching and flow rate zeroizing were significantly decreased. By the optimized analytical procedure and chromatographic conditions of 2DGC, determination of the 6 components was completed within 1 h without lossing of any of the components. Detection limits (3S/N) found for CO, CO₂, CH₄ and H₂ were 0.001 5%, 0.001 0%, 0.001 5% and 0.15% respectively. Values of RSDs (n=10) found for the above 4 gas components were 0.50%, 0.20%, 0.20% and 0.40% respectively. As shown by the results of test for significance, no significant differences were found among the analytical results found by 2DGC, by the MS and by CO detector. The proposed method had been applied to the analysis of actural samples, and as shown by the results of determination, CO, CO₂, CH₄, H₂, N₂ and O₂ were the main components in air after TNT explosion.