Geochemical analysis of hydrocarbon in Yakela Field shows that natural gas is characterized by dominant methane in content with a range of 79.13,～89.30, and by high content of heavy hydrocarbon with of average 9.67, and low dry coefficient (C1/C1-5) of 0.89～0.92, which suggests it is a typical wet gas. Carbon isotopic values of heavy gaseous hydrocarbon in which δ13C1 is -40.8 ‰ ~-39.4 ‰, δ13C2 is -32.0 ‰ ~-30.2 ‰ and δ13C3 is -30.5 ‰ ~-28.9 ‰ demonstrate that the gas is oil-prone. According to the chemical and carbon isotopic compositions of crude oil and the biomarker characteristics,the crude oil in the field derived from marine sources. The crude oil has been at high stage of maturity that is almost consistent with natural gas,which is inferred that both the oil and the gas are the products during one time of hydrocarbon-filling history so that the hydrocarbon in Yakela Condensate Field is distinct from that in Tahe oil Field.