A maintenance method for the Automatic Switched Optical Network, ASON, system when a service generates an alarm, the method characterized by comprising: Step A: after a service is successfully established, a head node setting a local alarm monitoring and respectively requesting an intermediate node and a tail node to set an alarm monitoring; and the intermediate node and the tail node setting their own local alarm monitoring according to the requests of the head node; Step B: when the intermediate node and/or the tail node generates an alarm, notifying the head node of alarm information which affects the service; Step C: according to the received alarm information, local alarm information of the head node and a protection and restoration strategy pre-configured by the head node, the head node setting a service maintenance strategy and a service maintenance operation, and notifying the service maintenance strategy to the tail node; Step D: the head node and the tail node carrying out corresponding maintenance operation according to the service maintenance strategy; wherein step C comprises: Step C1: the head node judging whether the service has a malfunction according to the received alarm information of a matching of the alarm monitoring nodes and the local alarm information of the head node; Step C2: when it is judged that the service has a malfunction, the head node setting the service maintenance strategy for the head node and the tail node according to the protection and restoration strategy pre-configured by the head node; Step C3: the head node sending the service maintenance strategy to the transmission plane of the head node, and transmitting the notify message with the service maintenance strategy to the tail node; wherein step B comprises: when the intermediate node or the tail node generates an alarm, their control planes sending the alarm information which affects the service to the head nodethrough the notify message according to the matching of the alarm monitoring nodes wherein a transmission plane alarm report is carried in the notify message, wherein the matching operation refers to determine the alarm generated by the time slot which bears service. Step A: after a service is successfully established, a head node setting a local alarm monitoring and respectively requesting an intermediate node and a tail node to set an alarm monitoring; and the intermediate node and the tail node setting their own local alarm monitoring according to the requests of the head node; Step B: when the intermediate node and/or the tail node generates an alarm, notifying the head node of alarm information which affects the service; Step C: according to the received alarm information, local alarm information of the head node and a protection and restoration strategy pre-configured by the head node, the head node setting a service maintenance strategy and a service maintenance operation, and notifying the service maintenance strategy to the tail node; Step D: the head node and the tail node carrying out corresponding maintenance operation according to the service maintenance strategy; Step C1: the head node judging whether the service has a malfunction according to the received alarm information of a matching of the alarm monitoring nodes and the local alarm information of the head node; Step C2: when it is judged that the service has a malfunction, the head node setting the service maintenance strategy for the head node and the tail node according to the protection and restoration strategy pre-configured by the head node; Step C3: the head node sending the service maintenance strategy to the transmission plane of the head node, and transmitting the notify message with the service maintenance strategy to the tail node;