Abstract: The Permo-Carboniferous strata of Bohai Bay Basin,the transitional facie,are the most important shale gas target strata in China which have a geologic gas accumulation condition.The sedimentary and geochemical characters show that the shale has a higher organic carbon and evolution degree.Overall,the organic geochemical characteristics of Taiyuan Group are better than those of Shan Xi Group,and the organic type is mainlyⅡ 2-Ⅲ which is in the pale of gas generating range.The optimization standard of favorable zone of shale gas in transitional facie is established in this study.The Jiyang Depression is selected as the advantageous area,its total payable acreage is 1675km²,mainly distribute in the west of Chezhen Sag,south of Huimin Sag and south of Dongying Sag.All the evidences proved that the carbonaceous mudstone of Permo-Carboniferous strata is the favorable bed for shale gas generation and accumulation,and it has the potential for shale gas exploration.