Based on the practical exploration in Paleogene of Jizhong Depression and Cretaceous of Erlian Basin for years, this paper puts forward a new concept on the hydrocarbon accumulation in troughs of faulted depressions, which includes the following findings. In troughs of faulted basins, the sandbody distribution is controlled by multiple factors, lithologic accumulations are more readily to form than structural accumulations, three factors control the formation of large hydrocarbon accumulations, and structural and stratigraphic-lithological reservoirs are not only co-exist but also complement each other. With the application of the concept, hundreds of million tons of oil reserves have been discovered in trough areas of the Huabei oilfield.