Disclosed is a method and a device for protecting service reliability, and the service reliability in the network virtualization system provided by the present disclosure may be ensured. In an embodiment of the present disclosure, a master node having a control function obtains the current service type information and notifies a slave node of the current service type information, for enabling the slave node to determine a main virtual link and a backup virtual link according to the service type information and to perform the failure detection, and when detecting that the main virtual link has failure and the backup virtual link has no failure, a service data message is switched to be transmitted on the backup virtual link, to ensure non-interrupted transmission of a service data message in a brand-new system architecture provided by the present disclosure, so as to ensure the service reliability.