Abstract. In allusion to scientific data isomerism and diversity as well as the lack of semantics in petroleum domain, this paper puts forward ontology-based semantic extraction method for heterogeneous data. Firstly, semantic extraction framework for scientific data in petroleum domain is constructed. On this basis, corresponding semantic transformation and abstract rules are worked out in allusion to structured and semi-structured data to form local domain ontology. Then, overall ontology in petroleum domain of data is constructed through dependence mapping among heterogeneous data. Effective organization and uniform management of heterogeneous data are achieved. Finally, correlation methods are applied in petroleum domain to provide support for effective management of petroleum scientific data and service sharing.