Based on the core and thin section observation, this paper analyzed the sedimentary system of Xujiahe Formation in Santai-Yanting area from the aspects of petrology, sedimentary structures, paleontology evidence and well logging. It is believed that the sedimentary system includes delta, lake and barrier coast. Among them, delta sedimentary system can be divided into braided river delta and meandering river delta in accordance with the different properties of water runoff into the water basin, furthermore, both of the braided river delta and meandering river delta can be subdivided into three sub-facies, including delta plain, delta front and prodelta. Lake sedimentary system consists of two sub-facies, including lakeshore and shallow lake. Barrier coast sedimentary system mainly consists of tidal flat sub-facies. On this basis, the sedimentary facies models of braided river delta and meandering river delta were established respectively, and the distribution characteristics and space allocating relation of facies and sub-facies in different periods of Xujiahe Formation in the study area were analyzed.