Considering the different workflow models in the world, Workflow Management Coalition proposes a XML based workflow process definition language, XPDL. It can be used to interexchange between different model representations. Therefore, it is important to map from an inner representation of the workflow model to  XPDL for exchange. To solve this problem, this paper first introduces the structure of XPDL,and then analyzes some general issues pertaining to the mapping procedure. Because most workflow enactment services are driven by the ECA rules, we propose a mapping algorithm from XPDL to ECA as an example to show the importance.