In view of the current tight oil research foci the concepts of tight oil, shale oil and oil shale are identi- fied and analyzed, and moreover the LTO ( light tight oil) is pointed out to be the conventional light oil in the low- permeability stratigraphic trap, which includes shale oil, sandstone oil and carbonate oil. This new concept has been recognized and applied by current mainstream foreign energy agencies. According to the screening criterions of tight oil reservoirs, the principal geological parameters of 14 typical reservoirs are figured out, the features of the tight oil in Songliao Basin are introduced, and furthermore 5 large-size and typical tight petroleum reservoirs are contrasted and induced the universality and specialility in their geological characteristics. In addition, the potential resources in the global tight oil are summarized and the main distribution, development preference and facing prob- lem are presented, the trends of the oil production rise in the different regions of the word are summarized. The re- searches show that tight oil is one of the important replacing petroleum resources in the world, and moreover has reached the top of the unconventional hydrocarbon development level, thus the future of the tight oil is very optimistic.