The invention discloses a QoS-aware service chain backup method and system. The service chain backup method comprises the following steps: a QoS-aware service chain backup problem is subjected to mathematical modeling, and QoS constraint conditions and a target function of the service chain backup problem are set; a service chain with the reliability lower than a reliability threshold is subjectedto backup of a virtual network function according to the QoS constraint conditions of the service chain backup problem, if the to-be-backed up virtual network function exists, an existing backup virtual network function is preferentially selected to serve as a shared backup, and if the to-be-backed up virtual network function does not exist, a new backup is created; and a final service chain backup scheme is determined according to the QoS constraint conditions and the target function of the service chain backup problem. According to the QoS-aware service chain backup method and system, the QoS requirement is combined with the backup process, the sharability of the backup network function is considered, therefore, excessive backup of the VNF is reduced, and the resource utilization efficiency and reliability of the service chain are improved.