In geology field, the rock attribute is the reference to,judge the strata relationship between boreholes. It is the key issues to transfer the qualitative attribute to quantitative data by using of Geo-ontology. Being a case of Geo-ontology the Stratum-ontology is a formalized representation and an instance to meet the quantitative need. According to the domination features of Carbonate rock, the semantic contents of Stratum-ontology are defined. Based on the construction of Stratum-ontology, the formal representation of semantic with BNF normal form is developed, which is the criterion for the judgment of stratum relation. According to the judgment and stratum inference rule, a digital three-dimensional geological model of a research district is constructed as a case.
