The design-workflow is a non-fair loop, which increases the risk that the workflow will fall into an infinite loop state because the workflow net is in a live lock state. In view of the above problems, an extended workflow network (EWF-net) based on an object-oriented Petri-net is presented. This method uses a state transition mechanism known as “jump-turning” and identifies the state of a workflow net using a “virtual token.” The role of jumping and virtual tokens are to move the workflow from an infinite loop to a finite number of iterations. To correctly describe the workflow net status when adding virtual tokens, an extended linear algebra approach used reachability analysis is presented. Finally, to verify the effectiveness of the proposed method, the EWF-net is used to model the missile design workflow, and the analysis method is used to investigate the reachability of the model. The results show that EWF-net can effectively solve the live lock problem of the design-workflow net.