Abstract: There are five series of oil-and-gas exploration layers that occur in Northeast China, of which the Upper Cretaceous Songhuajiang Group distributed extensively in the Songliao basin has been treated as the predominant layer, which however has gradually lost its capability of oil-and-gas production at the late stage of stable production as compared with the Lower Cretaceous layers in Songliao, Erlian, Hailar and other basins which are at the culminating stage of exploration. Researches show that there most probably exist desirable layers of Middle-Lower Jurassic that have been preserved well underneath the Cretaceous basins (even under the Upper-Jurassic volcanic rocks). Recently, the Upper Paleozoic oil-and-gas bearing layers have been generally regarded as a remarkable potential prospective area on the basis of extensive work. Meanwhile, the coal and oil shale deposits of the Cenozoic period distributed widely in the fault depression basins might serve as good indicators to trace their underlying Cretaceous oil-and-gas bearing layers in the eastern region of Northeast China. According to the characteristics of the above-mentioned five Cretaceous layers with different ages, this paper suggests that the conventional and unconventional oil-and-gas exploration should be focused mostly on the newly-discvoered oil-and-gas bearing layers and areas.