The invention discloses a protection method used for the link aggregation group of an Ethernet ring network and a device thereof; wherein, the method comprises the steps as follows: the state of the physical link in the link aggregation group is detected; when the failure state of certain physical link in the link aggregation group exists, the current wideband of the aggregation link group is compared with the inverse threshold value which meets the practical service requirement; furthermore, according to the comparison result, the subsequent processing is carried out; the protection method and the device thereof can meet the wideband requirement of the user.