Abstract: In view of the main feature of strong anisotropism of reservoir Stratum of the Paleozoic Era carbonate rock in the middle part of Ortos basin gas field, mainly by means of random analog formation, this paper makes a quantitative tranformation on the geological study on the area and the descriptive results of the gas pool, and finishes the whole geological model of underground carbonate rock in Ortos basin, including the structure model/physical model and fluid distribution model. Based on the model,the paper also makes a risk evaluation of the reserves,genevaizes the relationship between the gas well capacity and the geological condition,and provides reference data about the best location of well and network parameter about gas pool numerical simulation.