The process tree has both the behavior and the structure of process model, and it is significant on simplifying the complexity of the process model. Existing methods can only transform the block structured process model into process tree. However, it is difficult to transform process model with complex structure into process tree. To solve this problem, a generating algorithm for the behavior equivalent process tree based on complete finite prefix unfolding is proposed. The algorithm is used to transform the process tree in behavior equivalent's process model into behavior equivalent process tree. This algorithm analyzes the process model based on an incomplete prefix unfolding technique and extracts the relationships between process model activities. After analyzing the activity relation, the algorithm reconstructs the process model. The behavior equivalent process tree is constructed through activity relation judgment and the iterative operation of model reconstruction. The validity and feasibility of the proposed algorithm in the generation of behavioral equivalent process tree are verified by experiments on the test model.