Abstract: Oil and gas genesis and accumulation patterns in different tectonic zones in the Fulongquan Subsag, Changling Depression, Songliao Basin, were determined according to natural gas composition, light hydrocarbon, carbon isotope, biomarker compounds and geologic conditions. The natural gas in the Quantou (K₁q) and Denglouku (K₁d) formations are mainly coal gas and condensate oil associated gas, mainly sourced from the Lower Cretaceous Shahezi Formation (K₁sh) and partially from the Yingcheng (K₁yc) and Huoshiling (K₁h) formations. There are two reservoir-forming modes:One is the reservoir formation model of secondary oil and gas reservoirs under deep fault control, and has the characteristics of "near source, deep fault transmission and strong reversal adjustment" in the steep slope zone; the other is the lateral migration oil and gas accumulation model in the gentle slope zone. In the Fulongquan area, the oil and gas source conditions and the transport conditions are favorable. The Lower Cretaceous strata include three sets of source rocks and a reticular transport system which consisted of Y-type faults and multiple regional unconformities. The strong tectonic inversion at the end of the Nenjiang Formation formed a large number of inversion structures, which provided a favorable trapping condition. Therefore, the Fulongquan area has some potential for oil and gas exploration.