Abstract: The ranges of permeability among low permeability, extra-low permeability and ultra-low permeability reservoirs are redefined, and the tight oil reservoir and low permeability reservoir are distinguished. The tight oil formation forming mechanism and development features are discussed, and the difference between Bakken tight oil reservoir and the common low permeability reservoir is pointed out. Also, the paper presents the key technologies and new knowledge of developing tight oil reservoirs in the Bakken play. The new technology and theory of developing Bakken tight oil reservoirs can provide low permeability reservoir development in China with a certain referential value.