Based on the molecular and stable carbon isotope compositions of over 60 gas samples collected from more than 10 exploration wells, in combination with the analytical data of source rocks and reservoir bitumen, the geochemical characteristics and origin of gases from the Puguang gas trap and other gas traps in Xuanhan\|Daxian region of the eastern Sichuan Basin have been investigated. Results indicate that the natural gases in the Feixianguan and Changxing reservoirs of the traps belong to dry gas with high amounts of H2S, and show a molecular composition feature of the gas cracked from oil in the traps. The gases are dominated by methane with dryness index mostly more than 0.99, and contain abundant non\|hydrocarbon components with CO2 and H2S being 5.32% and 11.95%, respectively. The methane is isotopically heavy (－29‰~－33‰ ), suggesting a high level of thermal maturity, and the δ13C values for ethane range mainly from －28‰ to －33‰ indicative of sapropelic organic source. The studied gases are believed to have a common source with the gases from the same reservoir age strata in the adjacent gas fields of the eastern Sichuan basin, but different in origin from Carboniferous gases due to different molecular and carbon isotope compositions. The compositions of biomarkers and carbon isotopes indicate a genetic relationship between the reservoir bitumen and the source rock in upper Permian Longtan Formation. The carbon isotope correlation between ethane in the natural gases and source rock kerogens shows that the gases in the reservoirs were mainly derived from Permian strata.