Abstract: In Jiyang depression the biogenic gas was first found from the first member of Shahejie Formation in Yangxin Subsag, and it came from a set of well-developed dark mud shales at the same layers. In order to know whether the mud shales have the conditions of forming biogenic shale gas, the conditions of source-reservoir-preservation were anatomized. The results show that the mud shales are at the stage of high hydrocarbon generation, with the characteristics of shallow burial, large thickness, wide distribution, appropriate geochemical analysis parameters as well as America gas-rich shales, well developed micropores and microfractures, some sandstone and carbonate thin-interlayers, better tectonic background, and so on. According to the results, the mud shales have the conditions of forming biogenic shale gas, so it means a good prospect for biogenic shale gas exploration in Jiyang depression.