Abstract: SDAI provides a data access interface independent of data storage systems. Studying C late binding of SDAI on relational database system, we argue that schema translation, data dictionary schema and SDAI data access strategy are the three interrelated aspects of a complete SDAI implementation. To achieve the least loss of data semantics and efficient access of STEP data, we give emphasis on the translation of EXPRESS inheritance, organize data dictionary according to the schema translation method, and discuss three SDAI data access strategies in different application environments.