Abstract: In vast Northwest China, there are numerous middle-and small-sized basins, which belong to different tectonic units and have different basin-forming backgrounds and reservoir forming conditions. In these middle-and small-sized basins, there are four sets of major hydrocarbon source rocks, namely Carboniferous, Permian, Jurassic and Cretaceous hydrocarbon source rocks, with good prospects for oil and gas exploration. However, every specific basin has a specific condition, which is different from the others. On the basis of the sufficient collection of previous research findings, the tracking of dynamic exploration and new discoveries of hydrocarbon, some typical basins with low-middle exploration degree have been selected as research objects in this paper, the hydrocarbon resource extents of these basins or sags have been evaluated and predicted through utilizing different quantitative calculation methods of resources, and the hydrocarbon resource potential within these middle-and small-sized basins have been analyzed respectively. The results show that, although many difficulties and bottlenecks exist in the works of oil and gas exploration, but there are a number of oil and gas exploration fields. For example, Jurassic and Cretaceous hydrocarbon-generation sags are favorable areas for hydrocarbon exploration. The near-source ancient uplifts and foothill belts are also favorable for oil and gas exploration, while the Carboniferous strata are a potential exploration area. In addition, unconventional hydrocarbon resources shall be worth considering.