Data updating method, device and system

The invention discloses a data updating method, device and system. The data updating method includes that after receiving new version resource, calculating the difference between a new version source packet and each of stored historical version resource packets according to a difference algorithm, and using the difference as an incremental difference packet of each historical version resource packet; storing each incremental difference packet, and recording the mapping relationship between the packet identification of each historical version resource packet and the corresponding incremental difference packet storage address; if an updating request carried with the version resource packet identification to be updated is received, confirming the packet identification of the historical version resource packet of which the identification value is the same with the identification value of the version resource packet identification to be updated; finding the incremental difference packet storage address according to the confirmed packet identification, and responding to the updating request and returning the found incremental difference packet storage address. The data updating method, device and system are capable of quickly finishing data updating under low bandwidth requirement, the bandwidth resource and energy consumption are saved, and the download time of the user is saved.