This application provides a message generation method, a message processing method, a message generation apparatus, and a message processing apparatus. The message generation method includes: obtaining, by a first device, a segment identifier list SID list, where the SID list includes a plurality of segment identifiers SIDs, the first N bits of the plurality of SIDs are the same, and N is a positive integer; generating, by the first device, a first message based on the SID list, where the first message includes a first part and a second part, the first part includes the first N bits of the plurality of SIDs, and the second part includes bit N+1 to bit 128 of each of the plurality of SIDs; and sending, by the first device, the first message to a second device.