Based on the core and thin section observation，the sedimentary system of Xujiahe Formation in the Southern Sichuan from the aspects of petrology，sedimentary structures，paleontology evidence and well logging. on the basis of regional formation, sedimentary characteristics and sedimentary evolution model of group carried on the thorough analysis.It is believed that the sedimentary system include delta，lake and barrier coast. Among them，delta sedimentary system can be divided into braided fiver delta. in accordance with With the different properties of water run off into the water basin，Results show that the area should be as a center of delta, lake and barrier coast multi-types sedimentary system is complex. Lake sedimentary system consists of two sub-facies，including lakeshore and shallow lake．Barrier coast sedimentary system mainly consists of tidal flat sub—facies．The delta sedimentary system of braided river delta sedimentary system, in the light of the different nature of entering water storage basin can be divided into lake delta and Marine delta, lake lakeside and shallow lake sedimentary system development two subfacies deposition; Barrier coast tidal flat sedimentary system development and deposition. On this basis, respectively established the Marine，terrestrial transitional facies and continental three types of sedimentary facies model. Episodic structural movement characteristics of the area,Xujiahe formation in different periods of sedimentary facies distribution characteristics and the control factors.