By optimizing the detecting conditions, the authors obtained the best condition for analyzing carbon dioxide, oxygen and nitrogen in debris top gas by GC in a single run. Accuracy and precision were used to evaluate the method. It is shown that this method has high accuracy and precision. This method is characterized by simple chromatographic conditions, fast analysis speed and small gas volume and it has been proved to be effective in known areas. It can be used to analyze carbon dioxide, oxygen and nitrogen in geochemical subsurface exploration samples, simulated samples and natural gas samples.