A method and a device for processing a packet by using a unified SR label stack, relating to the field of PTN. The method includes: allocating, according to a type of a forwarding plane, a compatibility indicator indicating that a unified U-SRH is carried, for a service packet entering the forwarding plane; adding an SR label stack, the U-SRH and the compatibility indicator to the service packet to obtain an extended packet; and processing and forwarding the extended packet in the forwarding plane according to the SR label stack, the U-SRH and the compatibility indicator. According to embodiments of the present disclosure, the unified SR label stack is used to simplify an application of SR technology in different forwarding planes, and uniformity of SR encapsulation format is enhanced.