A method, a device, and a system for protecting a multicast traffic in the field of mobile communication are provided. A backup path is set up for a path that needs to be protected. Route information of the backup path is pre-stored in an entry of a route table. When a failure of the path is detected, a traffic is switched from the failed path to the backup path. By setting up a unicast tunnel or a multicast tunnel as the backup path for a working path in the multicast in advance, and by adding a backup path port as an ingress port of an entry of the route table, it realizes to switch a data flow to the backup path at a forwarding layer without being detected by a user when the working path failure occurs, realizes a fast convergence, and does not influence a user experience, thereby effectively reducing the influence on the user experience when the failed path is restored in a point-to-multipoint service.