Abstract: Lithophase is the response of lithology and porosity, and it has an important cont rolling effect on the dist ribution of water and oil.Every lithophase have similar logging response, lithology characteristic and relationship of porosity and permeability.In this paper, the logging response of MRIL and FMI have been analyzed by using electrofacies analysis technique.The whole reservoir is divided into several lithophases according to logging response, well logging evaluation models have been constructed, and criterion to identify oil-water layers for different lithophase have been determinated.Through this study, the accuracy of oil-water layer identification has been improved from 60% to 80%, and the difficult problem to identify oil-water layer has been solved.