A cross-blockchain data migration method includes obtaining, by a first node in a first blockchain network, from a first blockchain in the first blockchain network, first service data information corresponding to a first data structure mode stored in a first block in the first blockchain and obtaining a second data structure mode associated with a second block in a second blockchain corresponding to a second blockchain network. The method further includes converting the first service data information to second service data information corresponding to the second data structure mode and establishing a hash mapping relationship between the first service data information and the second service data information in the first blockchain. The method also includes migrating the second service data information to a second node in the second blockchain network based on the hash mapping relationship.