Abstract: The area of northwest China is 260×10⁴km² and more than 100 oil and gas fields have been discovered in the area.It has rich hydrocarbon resource.The characteristics of oil generation in compressional superimpositional basins were summarized after tens years of exploration and study.They are Characte-rized by polycyclic evolution,complicated tectonic deformation,multiple-age source rocks,multiple combinations of reservoirs and seals,multistage accumulation,and unique properties and distribution of oil and gas fields.