A method for processing a service flow in a packet network, wherein the method is applied to a network device group, the network device group comprises a first network device and a second network device, the first network device is connected to the second network device, the first network device communicates with a third network device, the second network device communicates with a fourth network device, and the method comprises: obtaining, by the first network device, a first upstream service flow, wherein the first upstream service flow comprises at least one upstream data packet, each upstream data packet in the first upstream service flow comprises a sequence number, the sequence number comprised in each upstream data packet in the first upstream service flow is used to identify a sequence that is in the first upstream service flow and that is of the upstream data packet comprising the sequence number, and the first upstream service flow is an upstream service flow received by the first network device from the third network device, or is a service flow obtained by the first network device by replicating an upstream service flow from the third network device; receiving, by the first network device by using a first pseudo wire, a second upstream service flow sent by the second network device, wherein the second upstream service flow comprises at least one upstream data packet, each upstream data packet in the second upstream service flow comprises a sequence number, the sequence number comprised in each upstream data packet in the second upstream service flow is used to identify a sequence that is in the second upstream service flow and that is of the upstream data packet comprising the sequence number, and the second upstream service flow is an upstream service flow received by the second network device from the fourth network device, or is a service flow obtained by the second network device by replicating an upstream service flow from the fourth network device; obtaining, by the first network device, a third upstream service flow based on a first reference sequence number and a sequence number comprised in each upstream data packet in N received upstream service flows, wherein the third upstream service flow comprises at least one upstream data packet, the N upstream service flows comprise the first upstream service flow and the second upstream service flow, and a sequence number comprised in any upstream data packet in the third upstream service flow is greater than the first reference sequence number; and sending, by the first network device, the third upstream service flow to a fifth network device. obtaining, by the first network device, a first upstream service flow, wherein the first upstream service flow comprises at least one upstream data packet, each upstream data packet in the first upstream service flow comprises a sequence number, the sequence number comprised in each upstream data packet in the first upstream service flow is used to identify a sequence that is in the first upstream service flow and that is of the upstream data packet comprising the sequence number, and the first upstream service flow is an upstream service flow received by the first network device from the third network device, or is a service flow obtained by the first network device by replicating an upstream service flow from the third network device; receiving, by the first network device by using a first pseudo wire, a second upstream service flow sent by the second network device, wherein the second upstream service flow comprises at least one upstream data packet, each upstream data packet in the second upstream service flow comprises a sequence number, the sequence number comprised in each upstream data packet in the second upstream service flow is used to identify a sequence that is in the second upstream service flow and that is of the upstream data packet comprising the sequence number, and the second upstream service flow is an upstream service flow received by the second network device from the fourth network device, or is a service flow obtained by the second network device by replicating an upstream service flow from the fourth network device; obtaining, by the first network device, a third upstream service flow based on a first reference sequence number and a sequence number comprised in each upstream data packet in N received upstream service flows, wherein the third upstream service flow comprises at least one upstream data packet, the N upstream service flows comprise the first upstream service flow and the second upstream service flow, and a sequence number comprised in any upstream data packet in the third upstream service flow is greater than the first reference sequence number; and sending, by the first network device, the third upstream service flow to a fifth network device.