This paper brings up a design of XML-based workflow engine and gives an implementation of a web-based workflow management system. Workflow is the automation of business procedures and workflow engine is the key part to carry out the system. Workflow engine can supply the conditions needed for executing a workflow process. This paper focuses on the workflow description language[1,5]--X-WPDL (XML-based Workflow Process Definition Language) that we designed and the implementation of the engine. All of the workflow processes that our engine operates are all described by X-WPDL. The engine translates the workflow process into an execution sequence that is consist of events or activities, then loads it in and drives it to run. The engine also offers an interface for the manager and participants for interaction. The application case will show that our implementation of this engine and the whole system is capable of processing workflow.