A hitless multi-carrier spectrum migration method and apparatus are disclosed. The method includes: obtaining a spectrum of a secondary carrier and a to-be-migrated carrier in a target carrier group from a network management system, and generating the secondary carrier according to the spectrum of the secondary carrier; sending a migration notification to a peer network device, and performing answer response to the migration notification from the peer network device, where the answer response is used to determine that network devices at both ends can perform spectrum migration; sending migration signaling to the peer network device; and receiving the migration signaling sent by the peer network device, and migrating, according to the migration signaling, overhead information and a service that are borne on the to-be-migrated carrier in the target carrier group to the secondary carrier.