This paper presents a 2—phase schema transformation method for schema transformation from relational databases into object—oriented semantic databases．The method is based on the semantics identmcation．The semantics included in local relation schemas can be divided into two parts：one are intra—relation semantics existing within local relations and the others are inter— relation semantics existing among local relations．All intra—relation semantics are captured into the global integration schema in phase l，and all inter—r elation semantics are enriched into the global integration schema by schema reconstruction operations in phase 2．The mapping rules and transformation operations are defined for setting up the transformation mechanism，and a set of algorithms and transfor mation formulations are provided for generating G—relations．