Knowledge flow is the knowledge creation, distribution, and reuse among participants. In knowledge intensive organizations, business process control and knowledge assess management are closely related to each other. Workflow management is an important technology for business process control. Yet knowledge management mechanisms can not be represented by current workflow process definition meta models. An innovative extended workflow process definition meta model is first proposed for integrating the above two aspects. Based on that, modeling and control of knowledge flows are studied. A knowledge flow modeling approach is proposed by using five kinds of knowledge flow components to represent knowledge distribution and reuse, cooperation and communication among participants. To deal with dynamic elements in knowledge flows, an adaptive knowledge flow control approach with corresponding algorithms is proposed based on resource constraints, changes of knowledge requirements, and time constraints. This paper presents a beneficial approach for the effective integration of workflow and knowledge management technologies.