The source and thermal evolution history of organic matter for the Longmaxi shale are still debated. This study analyzed the molecular and stable carbon isotopic compositions of hydrocarbons (CH 4, C 2H 6, and C 3H 8) and CO 2 as well as the stable hydrogen isotopic compositions of methane, ethane, and noble gases (He, Ne, Ar, Kr, and Xe). Shale gases in the WY and CN areas show an extremely-low-wetness with CH 4 concentrations range from 93.41% to 99.01%. Non-hydrocarbon gases are mainly N 2 (0.22%–2.81%) and CO 2 (0.03%–1.35%). H 2S have not been detected. Different δ 13C 1 and δ 13C 2 values in WY and CN shale gases (WY: −37.3‰ to −35.0‰ and −40.3‰ to −38.3‰, CN: −29.8‰ to −26.3‰ and −35.3‰ to −32.7‰) and various carbon isotope-composition distribution patterns (δ 13C 1>δ 13C 2<δ 13C 3 and δ 13C 1>δ 13C 2>δ 13C 3) of hydrocarbons indicate a complex evolution process. WY shale gases include more oil-cracking gas than CN shale gases, suggesting WY shale gases more like come from Type I-II organic matter. In shale gas systems, methane content and δ 13C 1 ratios vary with the degree of thermal evolution, so the origin of shale gas cannot be determined using carbon isotope data alone. The wide range of δ 13C CO2 values (−8.9‰ to −0.8‰) and N 2/ 40Ar ratios (20.8–165.1) suggests multiple origins of the gases. Emeishan mantle plume provides the source of heat for some thermo-genic gas. Noble gas isotopic compositions ( 3He/ 4He: 0.001Ra to 0.019Ra) indicate air and crustal origins with no significant contribution from the mantle. 40Ar/ 36Ar ratios (1194.3–4604.5) are consistent with the age of Longmaxi strata calculated by accumulative effect of Ar isotope. The shale gas humidity, carbon isotope ratios, and the carbon isotope-composition distribution patterns may contain information indicating the shale gas sweet spot.