Automated model transformation from PIMs to PSMs is a pivotal challenge of model driven development. Since models are usually represented in a graphic manner of class diagram (CD), current graphic-transformation based approach seems to be a natural approach. To overcome deficiencies of this approach, i.e. insufficiency of direct support for CD and explicit formal definition, we define a transformation definition metamodel, which employs the rule template match technique. The rule iteration algorithm and the rule schedule algorithm form the computing model. We also define and implement a transformation rule set for the transformation from UML class models to EJB models. Explicitly formal definition, transformation metamodel and demonstration make our work comprehensible and applicable. Besides MDD, our work also has potential to be applied in software evolution and integration.