Business process verification is an important topic in business process management (BPM). The verification of standard UML Activity Diagram is not easy due to lack of mature tools. YAWL (yet another workflow language) has a formal semantics based on Petri net; verification of YAWL model seems easier than other modeling languages such as UML-AD. A series of mature verification tools has been released (Woflan, WofYAWL, ProM) based on YAWL to find structural errors, such as deadlocks in the model. These tools can be used for verifying UML-AD models if they can be transformed to YAWL models.The most challenging problem is that some control-flow patterns in UML-AD can’t be transformed via an element-to-element mapping. To solve this problem we provide a control-flow pattern based method for transforming a UML-AD model to YAWL. We regard these patterns that need to be transformed as whole model segments, pick them out from the UML-AD model and transform the left part using an element-to-element mapping as well as an object flow transforming method. We subsequently transform the picked-out patterns via patterns-based transformation and combine all the transformed YAWL segments to a new YAWL net.Categories and Subject Descriptors: D.2.1 [Requirements]: Requirements –Methodologies.General Terms: Theory.