By studies of outcroped profiles at the rim of Sichuan basin and the core-sections in Yuanba Area , it,s been revealed that Xujiahe Formation might be assigned to coast system products,but not the continental deposits as commonly inferred to since 1950s,.The 2nd Member of Xujiahe Formation is thought to be tide-dominated estuarine in origin, including the facies of alluvial Channel,tidal-fluvial channel,UFR sand flat,tidal bar,mud flat and salt swamps.However,the 4th Member of the formation is regarded as the products of tide-dominated delta, including the facies of delta-plain channel, distributary-mouth tidal bar,delta front,prodelta,mud flat and salt swamps.Both of the tide-dominated estuary and delta are geologically ephemeral,they can only form in the presence of a relative sea-level rise (i.e,a transgression).If the rate of sediment supply is sufficient,they become filled up(regression),the sites then become tidal flat-strand plain environment(deposites) which correspond to the coal-bearing fine-grained successions of the 3rd and 5th Member of Xujiahe formation .Basing on the close corelationship between reservoir quality and sedimentary facies,5 types of reservoir facies were divided.Exloration suggestions were proposed according to our successful experiences in studying the Xujiahe Formation in Anyue Area.