Abstract: The low rank coal CBM geology, including reserve condition, reservoir parameters and resource, is discussed in a case of Jurassic formations in Ordos Basin.Through this study it is indicated that the Jurassic formations' coals in Ordos Basin are characterized by low rank, more coal bed targets, big thickness, favorable hydrological condition and resource.Contrasted with the CBM geological setting in Powder River basin in America, the Jurassic formations in Ordos Basin has certain development potential.It is known that the low rank coal CBM development is successful in America, and in China there is the extensive low rank coal distribution, the vast coal and CBM resource, the favorable geological condition.Therefore it is necessary to put more strengh to explore CBM reservoirs in Ordos Basin.