Abstract: Traditional workflow model focuses on dealing with predictable and predefinable processes. However those prerequisites cannot be counted upon any more in the modern enterprise environments, where the process definitions can't be finished at the design phase, but are to be completed at the end of process instances. Thus traditional WFMS aren't capable of managing the modern processes. We propose a flexible workflow model based on the combination of ECA rules and activity, with the ability to handle modern flexible processes in simple but applicable way. Furthermore we design a WFMS based on multiple agents in order to provide support for the flexible workflow model.