WWW is an open and distribution environment, which contains larger number of information. Using ontology can help user to get the network information. Ontology can realize the interoperability and reuse of ontology between each other by referencing relationship. For the rapid growth of WWW and the relative independence between web ontology, so how to integrate the ontology becomes the key problem to better support web ontology reuse. This paper proposes a method that transforms the ontology into the representation of first order predicate logic, and then put forward the method to check the consistency of ontology and integrate ontology.