How to balance the retrieval performance, maintenance cost and implementation complexity becomes one of the key elements in the research of OODB indexing. This paper proposes an approach for the indexing configuration of inheritance hierarchy. It estimates retrieval cost, storage cost and updates cost for all kinds of index configurations through cost model, and chooses optimal index configuration based on real database usage. The accuracy of this method is tested through experiments, and the performance of this method is compared with other indexing scheme. The results show that the proposed method can provide optimal indexing for OODB.