Lower Triassic Feixianguan Formation in Puguang Gas Field can be divided into three major depositional systems, include the carbonate rocks platform, the platform margin and the slope-basin depositional systems. The carbonate platform depositional system can be divided into open platform facies, restricted platform facies and evaporation platform facies. The platform margin depositional systems can be divided into platform marginal facies. The slope-basin depositional system can be divided into marginal slope facies, shelf facies and basin facies. Subfacies and microfacies can be further divided. Feixianguan reservoir mainly consists of dolostone in lithology. Oolitic dolostone, calcirudite oolitic dolostone and residual oolitic dolostone are the important reservoir rocks. It is indicated that the crystalline dolostone and micritic dolostone reservoirs are medium in reservoir property and other types of reservoir rocks are relatively poor in property.