A tree recovery method for a software-defined network (SDN) adapted to an SDN controller is provided. The tree recovery method includes: establishing topology information based on a current SDN topology and storing the topology information in a storage of the SDN controller; receiving a failure message reporting a failure link of the SDN, a plurality of network nodes of the topology information are classified into at least one losing nodes and at least one remaining node according to the failure link; and calculating and linking the at least one losing node to the at least one remaining node by using the topology information stored in the storage.