ass=MsoNormal style="MARGIN: 0cm 0cm 0pt">ang=EN-US style="FONT-FAMILY: ’Times New Roman’,’serif’">This paper aims to explore the evaluation methods of the marine shale gas resource potential. Taking the shale in Lower Carboniferous Datang Stage for an example, it mainly expounds the principle of key parameter selection involved by the unconventional shale gas resource potential volume method. The key parameters are selected one by one and analyzes the expected value through the discrete data conditional probability. The research obtains 11 key parameters of the shale in Datang Stage with the conditional probability of 5%, 25%, 50%, 75%, 95%.They are the area, thickness, total porosity, free-gas saturation, absorbed gas content, TOC, etc.. The resource potentialities of the shale in Datang Stage is preliminary estimated.amespace prefix = "o" ns = "urn:schemas-microsoft-com:office:office" />