Abstract: CWM(common warehouse metamodel) meta model is independent of any platform and products. Data warehouse tools are specific. Basing on the principles of MDA（model driven architecture） model transformation, CWM represents PIM(platform independent model), dw tools presents PSM(platform specific model), the mapping rules from PSM to PIM are set up, transformation ru
les from PIM to PSM are defined, metadata exchange between different tools is realized. According to above-mentioned, specific transformation rules are defined to implement the mapping between PowerMart.dtd (ETL（extract transform load） tool of informatica company) entity elements and CWM ones. And according to the semantics, the mapping is described formally so as to provide a solution for metadata interchange in the field of data warehouse.

Key words: model driven architecture, meta model, mapping rule, common warehouse metamodel