Abstract: Hailaer Basin is the Mesozoic and Cenozoic basin located in the Paleozoic orogenic belt in Inner Mongolia-Daxing??anling area. This basin is composed of a number of relatively independent rift groups controlled by the fault of northeastern direction. The basin mainly has Lower Cretaceous strata, namely Xing??anling Group, Tongbomiao Formation, Nantun Formation, Damoguaihe Formation and Yimin Formation. Three sets of hydrocarbon source rock, with a large thickness and a high content of organic matter, developed in Tongbomiao Formation, Nantun Formation and Damoguaihe Formation. The types of reservoirs main include base rock weathering crust, sandstone, tuffaceous sandstone and conglomerate. The low stand fan caused by the low stand systems tracts and the fan delta sand body caused by the high stand systems tracts are the main oil and gas reservoirs. A number of source-reservoir-caprock assemblages developed under the regional cap rock of Damoguaihe Formation. Vertically, the oil and gas are abundant mainly above and below the unconformity surface, shaping the oil and gas reservoirs of four types-faulted block, fault-lithologic, lithologic and buried hill. Horizontally, the oil and gas are abundant mainly the source groove and the nearby fault belts. The twisted fault belts are the favorable zones for oil and gas accumulation