The evaporate and oil-gas resources often coexist in the same basin, and evaporates are the quality covering strata for oil and gas deposits. This paper suggests a judging model for the lithology of the evaporate basin, which uses comprehensively geophysical prospecting logging data in the evaporate basin and then processes the logging data semi-quantitatively and qualitatively on the basis of expert knowledge. It gives experiential formula and expert knowledge data model and designs the basic implementation of algorithm. Model experimentation calculation for logging data from drill hole Yangta #5 shows that 84% of the results are identical to the known data, indicating that the model has a fairly good referencevalue for similar application.