Abstract: In order to explore the relationship between the coal accumulation characteristics and the sedimantary environment of Longtan Formation, this paper an alyzed the petrological characteristics, sedimentary environments and the evolution of Longtan Formation in Chaohu Area. Combined with the basic theory and method of sedimentology and coal geology, three kinds of sedimentary facies: delta facies, lagoon- tidal flat facies and carbonate platform facies were distinguished by means 0 f the measurement of field profile and indoor grain size analysis. Among them, the delta facies included two types of subfacies and five types of microfacies. The rusults showed that the coal- bearing strata of Longtan Formation area were mainly formed by delta plain swamp flling in Chaohu Aera, and the delta plain was the best place f or coal accumulation. Compared with other regions in southern Anhui Province, it was featured as thin seam, high layer position and high sulfur content. This could attri bute to the difference of sedimentary basement, sedimentary environment and forming time in Chaohu Area.