A data migration method, comprising: determining, by a first node in an optical channel payload unit-Cn signal, a second tributary slot corresponding to a first tributary slot, wherein the second tributary slot is an idle tributary slot (step 510); sending, by the first node in the second tributary slot, first migration information to a second node, wherein the first migration information is used to request to migrate a first low-order optical channel data unit service from the first tributary slot to the second tributary slot (step 1010); receiving, by the first node, second migration information that is sent by the second node in the second tributary slot according to the first migration information, wherein the second migration information is used to indicate that it is agreed to migrate the first low-order optical channel data unit service from the first tributary slot to the second tributary slot (step 1020); sending, by the first node in the second tributary slot, third migration information to the second node according to the second migration information, wherein the third migration information is used to indicate that an operation of migrating the first low-order optical channel data unit service from the first tributary slot to the second tributary slot is to be executed (step 1030); and migrating, by the first node, after a first multi-frame, the first low-order optical channel data unit service from the first tributary slot to the second tributary slot, wherein the first multi-frame is an x th multi-frame after a multi-frame used to carry the third migration information, and x is a positive integer greater than 1. determining, by a first node in an optical channel payload unit-Cn signal, a second tributary slot corresponding to a first tributary slot, wherein the second tributary slot is an idle tributary slot (step 510); sending, by the first node in the second tributary slot, first migration information to a second node, wherein the first migration information is used to request to migrate a first low-order optical channel data unit service from the first tributary slot to the second tributary slot (step 1010); receiving, by the first node, second migration information that is sent by the second node in the second tributary slot according to the first migration information, wherein the second migration information is used to indicate that it is agreed to migrate the first low-order optical channel data unit service from the first tributary slot to the second tributary slot (step 1020); sending, by the first node in the second tributary slot, third migration information to the second node according to the second migration information, wherein the third migration information is used to indicate that an operation of migrating the first low-order optical channel data unit service from the first tributary slot to the second tributary slot is to be executed (step 1030); and migrating, by the first node, after a first multi-frame, the first low-order optical channel data unit service from the first tributary slot to the second tributary slot, wherein the first multi-frame is an x th multi-frame after a multi-frame used to carry the third migration information, and x is a positive integer greater than 1.