The invention provides a method and a system for rebuilding single ring network topology. In the method, each node in the single ring network detects, at a predetermined time interval, whether the link connected with the root port of the present node is failed (S401); when one node in the single ring network detects a link failure, the node having a blocking port obtains the information that the link failure occurs in the single ring network (S403); and the node having the blocking port switches the state of the port in a blocking state to a forwarding state (S405). With the technical solution provided by the invention, the passive wait for obtaining the link failure can be converted to the active detection for the link failure, and the state of the port in the blocking state is directly switched to the forwarding state. Therefore, the convergence speed is accelerated.