How to modeling a business process is discussed in this paper, in which the task stream and the resource stream are concurrently occurred. A Resource/Task net (R/T-net) based on the timed Petri net and the modeling process by using R/T-net for workflow is proposed. The resource dependence and expectancy set in task model can be used to control the task transition, while the fire-rule and the routing-rule can be used to control cooperation, synchronism, assignment and transition of resource, so that it is more powerful than the Petri net in the workflow modeling,such as the office automation,the product manufing,the material transaction,and so on.