In this paper, we propose to define an ontology mapping meta-model based on set and relation theory, and it is the foundation of managing mappings among heterogeneous ontology models. The ontology mapping meta-model is composed of ontology related elements (OntologyElement, OESet, OESetGroup, GroupDefinitionRule, etc), mapping related elements (Mapping, MappingClassification, MappingDefinitionRule etc). Just because set and relation theory is the theoretical foundation of mapping models, the powerful computation capability of set and relation theory can be used in ontology mapping models computation. Simultaneously, model synchronization among heterogeneous ontology models is also introduced as an ontology mapping model application example. The primary contribution of this paper is to define an ontology mapping meta-model based set and relation theory which can be regarded as the unified mechanism to manage the large number of ontology models and their relationships.