The Permian is an important marine origin oil and gas bearing stratum. Two big transgressiveregressive sedimentary cycles have been recognized, which are responsible for a sedimentary palaeogeographic framework of coexisting marine facies, land facies and transitional facies, with marine carbonate rocks being dominant during the Permian. Based on lithofacies palaeogeography study and typical profiles analysis, four depositional systems, i.e. land depositional system, mixed depositional system, carbonate platform depositional system and slopebasin depositional system are recognized. Spatial relationships of different depositional systems are summarized, and four basic  depositional system associations are generalized. It is pointed out that the sealevel changes and tectonic movements are the key factors controlling the changes and spatial distribution of depositional systems. Finally, Permian oil and gas forming conditions —— generating, reservoiring, capping and their associations are analyzed. It is suggested that there are many associations of generating, reserroiring, capping in the Permian, among which the associations of carbonate platform system and slopebasin system, and mixed system and slopebasin system are the best ones.