Most requirement documents were written in ambiguous natural languages which are less formal and imprecise. Without modeling the requirement documents, the knowledge of the requirement is hard to be kept in a way, which can be analyzed and integrated with artifacts in other phases of software life cycle, e.g. UML diagrams in analysis and design phases. Therefore, maintaining the traceability and consistency of requirement documents and software artifacts in other phases is costly and error prone. In this paper, we propose a Model-based Object-oriented approach to Requirement Engineering (MORE). Applying modeling and OO technologies to requirement phases, the domain knowledge can be captured in a well-defined model, so the completeness, consistency, traceability and reusability of requirement and its integration with the artifacts of other phases can be cost effectively improved. A case study has shown the promise of our approach.