A multi-ring Ethernet protection method, characterized by comprising: determining, by a master node in a master ring, connectivity condition of the master ring and a state of a shared link; notifying, by the master node in the master ring, information of the determined connectivity condition of the master ring and the determined state of the shared link to a master node in a slave ring; and judging, by the master node in the slave ring, whether to open a slave port according to the information; wherein the shared link is a link shared between the master ring and the slave ring; wherein the steps of notifying the information of the connectivity condition of the master ring and the state of the shared link to the master node in the slave ring, and of judging whether to open the slave port according to the information comprise: the master node in the master ring sending a flush protocol message containing identification field to the master node in the slave ring, if the master node in the master ring determines that the master ring is disconnected and the state of the shared link is down, wherein the flush protocol message containing identification field carries one or more identification fields used for indicating the shared link and the number of identification fields; and the master node in the slave ring receiving the flush protocol message containing identification field, determining that the master ring is disconnected when judging that the flush protocol message containing identification field carries the number of identification fields, and opening the slave port; or the steps of notifying the information of the determined connectivity condition of the master ring and the determined state of the shared link to the master node in the slave ring, and of judging whether to open the slave port according to the information comprise: the master node in the master ring sending a flush protocol message containing identification field to the master node in the slave ring, when determining that the master ring is connected and the state of the shared link is down, wherein the flush protocol message containing identification field carries one or more identification fields used for indicating the shared link and a first predetermined value used for indicating connectivity of the master ring; and the master node in the slave ring receiving the flush protocol message containing identification field; the master node in the slave ring determining that the master ring is connected according to the first predetermined value carried in the flush protocol message containing identification field, and keeping blocking the slave port after determining that there is no link failure in the slave ring. determining, by a master node in a master ring, connectivity condition of the master ring and a state of a shared link; notifying, by the master node in the master ring, information of the determined connectivity condition of the master ring and the determined state of the shared link to a master node in a slave ring; and judging, by the master node in the slave ring, whether to open a slave port according to the information; wherein the shared link is a link shared between the master ring and the slave ring; wherein the steps of notifying the information of the connectivity condition of the master ring and the state of the shared link to the master node in the slave ring, and of judging whether to open the slave port according to the information comprise: the master node in the master ring sending a flush protocol message containing identification field to the master node in the slave ring, if the master node in the master ring determines that the master ring is disconnected and the state of the shared link is down, wherein the flush protocol message containing identification field carries one or more identification fields used for indicating the shared link and the number of identification fields; and the master node in the slave ring receiving the flush protocol message containing identification field, determining that the master ring is disconnected when judging that the flush protocol message containing identification field carries the number of identification fields, and opening the slave port; or the steps of notifying the information of the determined connectivity condition of the master ring and the determined state of the shared link to the master node in the slave ring, and of judging whether to open the slave port according to the information comprise: the master node in the master ring sending a flush protocol message containing identification field to the master node in the slave ring, when determining that the master ring is connected and the state of the shared link is down, wherein the flush protocol message containing identification field carries one or more identification fields used for indicating the shared link and a first predetermined value used for indicating connectivity of the master ring; and the master node in the slave ring receiving the flush protocol message containing identification field; the master node in the slave ring determining that the master ring is connected according to the first predetermined value carried in the flush protocol message containing identification field, and keeping blocking the slave port after determining that there is no link failure in the slave ring.