A method for processing a packet by using a unified segment routing, SR, label stack, comprising: allocating, by an ingress node, according to a type of a forwarding plane, a compatibility indicator indicating that a unified segment routing header, U-SRH, is carried, for a service packet entering the forwarding plane; adding, by the ingress node, an SR label stack, the U-SRH and the compatibility indicator to the service packet to obtain an extended packet; and processing and forwarding, by a forwarding node, the extended packet in the forwarding plane according to the SR label stack, the U-SRH and the compatibility indicator, wherein the allocating, by the ingress node, according to the type of the forwarding plane, the compatibility indicator indicating that the U-SRH is carried, for the service packet entering the forwarding plane comprises: in response to that the forwarding plane is a multiprotocol label switching, MPLS, or multiprotocol label switching transport protocol, MPLS-TP, forwarding plane, allocating an MPLS or MPLS-TP reserved label indicating that the U-SRH is carried, for the service packet as the compatibility indicator; in response to that the forwarding plane is an IPv6 forwarding plane, allocating an IPv6 extension header indicating that the U-SRH is carried, for the service packet as the compatibility indicator; in response to that the forwarding plane is an IPv4 forwarding plane, allocating a user datagram protocol, UDP, port number indicating that the U-SRH is carried, for the service packet as the compatibility indicator; and in response to that the forwarding plane is any other forwarding plane, allocating an extension header indicating that the U-SRH is carried, for the service packet as the compatibility indicator. allocating, by an ingress node, according to a type of a forwarding plane, a compatibility indicator indicating that a unified segment routing header, U-SRH, is carried, for a service packet entering the forwarding plane; adding, by the ingress node, an SR label stack, the U-SRH and the compatibility indicator to the service packet to obtain an extended packet; and processing and forwarding, by a forwarding node, the extended packet in the forwarding plane according to the SR label stack, the U-SRH and the compatibility indicator, wherein the allocating, by the ingress node, according to the type of the forwarding plane, the compatibility indicator indicating that the U-SRH is carried, for the service packet entering the forwarding plane comprises: in response to that the forwarding plane is a multiprotocol label switching, MPLS, or multiprotocol label switching transport protocol, MPLS-TP, forwarding plane, allocating an MPLS or MPLS-TP reserved label indicating that the U-SRH is carried, for the service packet as the compatibility indicator; in response to that the forwarding plane is an IPv6 forwarding plane, allocating an IPv6 extension header indicating that the U-SRH is carried, for the service packet as the compatibility indicator; in response to that the forwarding plane is an IPv4 forwarding plane, allocating a user datagram protocol, UDP, port number indicating that the U-SRH is carried, for the service packet as the compatibility indicator; and in response to that the forwarding plane is any other forwarding plane, allocating an extension header indicating that the U-SRH is carried, for the service packet as the compatibility indicator. in response to that the forwarding plane is a multiprotocol label switching, MPLS, or multiprotocol label switching transport protocol, MPLS-TP, forwarding plane, allocating an MPLS or MPLS-TP reserved label indicating that the U-SRH is carried, for the service packet as the compatibility indicator; in response to that the forwarding plane is an IPv6 forwarding plane, allocating an IPv6 extension header indicating that the U-SRH is carried, for the service packet as the compatibility indicator; in response to that the forwarding plane is an IPv4 forwarding plane, allocating a user datagram protocol, UDP, port number indicating that the U-SRH is carried, for the service packet as the compatibility indicator; and in response to that the forwarding plane is any other forwarding plane, allocating an extension header indicating that the U-SRH is carried, for the service packet as the compatibility indicator.