Data synchronization method, device and system

The application discloses a data synchronization method, a device and a system. The data in a change table of a source database is obtained as the current synchronization data; the data in the change table is extracted from the incremental change data of the source database, and is sequentially stored into a preset change table according to the extraction sequence and taking item as the unit; the current synchronization data is transmitted to a target database; and the receiving result information of the target database is obtained, and the current synchronization data in the change table is deleted if the receiving result information indicates that the synchronization data is successfully transmitted. According to the embodiment of the application, the change table recording incremental data of the source database is operated, instead, the source database is not directly operated, the source database is prevented from being invasively retrieved, and the performance on data synchronization is accordingly improved.