Abstract: The fractures of mudstone reservoir at Xianhezhuang ar- ea are classified as 6 types.How to indentify the mudstone fracture is studied,and the key factors to generate the frac- tures are identified as the tectonic stress and abnormal pres- sure.Meanwhile.the fractures are also subject to the sedi- mentary facies,the lithology of reservoir and the thickness of horizon.The fractures at Xianhezhuang area were genera- ted at the early sedimentary stage of Guantao formation when hydrocarbons in source rocks were generated and then expelled,thus bringing about rnudstone fracture hydrocarbon pool.