A method and a system for data migration are described, the method for data migration including: slicing data in an original system to obtain a data slice; importing the data slice into a new system; and redoing, in the new system, respective data corresponding to at least one pre-recorded write request according to a sequence number order of the at least one pre-recorded write request, wherein the at least one pre-recorded write request above is to simultaneously write to both the original system and the new system. In the method and the system, data in an original system can be seamlessly imported to a new system without forbidding writes to the original system, and the data in the new system can be recovered to the latest by a redo technique. Without any awareness of users, the data migration can be achieved in the background.