Abstract: Due to the difficulty of constructing sound workflow model, this paper maps the workflow model defined by workflow management coalition (WFMC) to workflow net (WF-net). Based on the definition of two adjustment mappings proved not to destroy structure properties and system behaviors, this paper adjust the WF-net to a complete extended free choice net (EFC-net). Proved the equivalent deadlock properties of EFC-net and free choice net (FC-net), this paper introduces an algorithm to obtain minimum deadlock. Finally, combined with rank theorem, an algorithm is given to verify whether a WF-net is soundness.