Mahu Sag is an important example of the application of the theory of the whole oil and gas system, Junggar Basin. The oil-gas reservoir pattern with normal and irregular distribution corresponds to the reservoir type with orderly distribution. In order to clarify its reservoir characteristics and control factors, the drilling, logging, analysis and laboratory analysis data of more than 50 Permian reservoirs in Mahu Sag are analyzed. The Permian sedimentary rock reservoirs in Mahu Sag are characterized by orderly lithology, facies and reservoir property from the edge of the sag to the depositional center. The lithology develops coarse clastic rocks, medium clastic rocks and fine-grained sedimentary rocks successively, and the grain size changes from coarse to fine in an orderly, continuous and sequential manner, which corresponds to the sedimentary facies changes. Coarse clastic rocks can be divided into rich shale conglomerate facies, shale conglomerate facies and lean shale conglomerate facies according to the level of shale content. Fine-grained sedimentary rocks can be divided into argillaceous lithofacies and dolomitic lithofacies according to the content of felsic and livid. The lean and argillaceous conglomerate facies and argillaceous rock facies have good reservoir property, and large-scale conventional conglomerate and unconventional shale oil reservoirs have been found respectively. Sedimentary facies control the orderly distribution of lithology, and gravity flow, torrent, traction flow, heavy flow and light flow dynamic fluid are closely related to the orderly distribution of lithofacies. The content of argillaceous complex and the composition of felsic mineral have decisive influence on the reservoir property of coarse clastic rock and fine grained sedimentary rock, respectively, and compaction diagenesis has important influence on the reservoir property of medium clastic rock. The orderly distribution of sedimentary rocks and the regularity of their reservoir properties control the gradual transition of oil and gas from continuous unconventional reservoirs to discontinuous conventional reservoirs.