The invention is a method for realizing automatic topology discovery of a kind of elastic grouping multi-ring mutual-connection method, at first, the standardized grouping ring RPR single ring network media is accessed to the address which controls the MAC, the representation method is defined extensively, then constructs the double direction chain and the topology information table unit structure of the tree connection, in order to preserve the topology information and the joint information in the network, finally, based on the constructed chain table and the automatic topology discovery., it uses clockwise layering method to realize the automatic topology discovery of the multi-ring mutual-connection network. The invention has character of distributed automatic control of single ring structure and the merits of automatic topology discovery algorithm, it solves the problem of route information automatic discovery and the automatic control of the RPR multi-ring mutual-connection network topology, based on the topology information and the joint information in the chain table and the information table, it can complete the calculation of the second layer route, thus, any joint in the network can works out the route series to other joint in the network quickly.