The reservoir quality is strongly influenced by the depositional microfacies，composition and grain size of sandstones，and diagenesis of the Chang 8 subaqueous distribution channel sandbodies of Upper Triassic deltafront facies in Fuxian. Depositional microfacies belts controlled reservoir by sand body types and characteristics of properties. Reservoir performances of sandbodies show significant difference in different depositional microfacies. Porosity and permeability of subaqueous distribution channel sandbodies in deltafront is the highest in related sandbodies，and interdistributary bayisthe worst by small granularity，more matrix，strong mechanical compaction prevented flowing of late dissolution fluid. The strong mechanical compaction，pressuresolution and cementation of authogenetic minerals reduced reservoir performances of sandstones. Dissolutions caused by freshwater leaching and organic acids have significance for improving reservoir.