The invention discloses an incremental multi-replica data synchronization method and system. The method includes the steps that a first operation record of a local replica and a second operation record of a far-end replica are acquired; whether the first operation record and the second operation record are consistent or not is judged; if not, synchronization operation is executed according to inconsistent content in the first operation record and the second operation record to ensure that the local replica and the far-end replica are consistent, and the synchronization progress is recorded. According to the data synchronization method and system, metadata is stored in a metadatabase, and as neither modification of content data nor modification of the metadata involves modification of the metadatabase, incremental synchronization can be achieved according to a modification log of the replica metadatabase; besides, the modification history of large files is deduced according to transaction logs of data, it is not needed to maintain extra log files, on the aspect of consistency, it is only needed to guarantee the consistency of the metadatabase and data files, and thus the implementation cost is greatly lowered.