Abstract: Guided by the depositional models of marine carbonate rocks, the sedimentary facies of the Late Permian Longtan strata in the Xuanhan-Daxian region is interpreted on the basis of sedimentary facies of single wells, drilling as well as surface outcropping data. The sedimentary facies in the region is typical gen-tle slope stagnant sea which produced large scale black mudstone and dark limestone. Through geochemistry analysis, it is confirmed that this source rock is a type of the important source rocks in northeastern Sichuan. The kerogen of this source rock is very good. This source rock contains a great deal of organic matters. The content of TOC varies from 0.5% to 27.1%, the average TOC is 2.91%, and most Of them are 3%-5%.