To solve the problem on coupling of activities and cooperators in classical workflow model, and improve the task distribution flexibility and adaptability, the competence concept for workflow activity and cooperator was presented. The competence ontology model and competence-based task organizing principles were described. A process meta-model was constructed based on the three-layer architecture of activity/competence/cooperator. A series formal description of competence matchmaking policy was put forward. These concepts and methodologies are implemented and verified in an open workflow system-ABCflow.