Modularization is a software engineering method, and it has been introduced into the domain of ontology in recent years to support ontology reuse  and ontology integration. The existing work does not discuss the modularization problem of ontology knowledge base which includes TBox and ABox at the same time. Based on the definitions of ontology knowledge base module and conservative extension, we propose a verification algorithm for the conservative extension of knowledge base, and theoretically prove that it can be used to verifiy whether an ontology knowledge base is a module of another knowledge base.