Abstract: Focused on the problems of object migration for object-oriented XML data，two approaches based on distributed and centralized storage model are put forward，each of which resolves the OID ambiguity problem.The second approach supports a single OID for a migrating object，and the updating of existing references can be expensive.The first approach supports multiple OIDs for an object as it migrates from one class to another along ISA hierarchy，and has relatively less overheads.