A data processing method, for being executed by a local electronic device for image data synchronisation with those of another device, characterized in that, the method comprises: acquiring, by a local device, first image data of images stored in the local device and second image data of images stored in another device; comparing, by the local device, the first image data with the second image data to determine a storage type of an image contained in the first image data and/or contained in the second image data by determining whether the image is stored in one, the other or both of the local device and the another device based on a storage path or a message digest contained in the first image data and contained in the second image data, the storage type comprising: both storing in the local device and storing in the another device, or only storing in the local device, or only storing in the another device, wherein the first image data further contains first face data of an image stored in the local device and a first face group corresponding to a face contained in the first face data, the second image data further contains second face data of an image stored in the another device and a second face group corresponding to a face contained in the second face data; establishing, by the local device, a mapping relation between a first face group contained in the first image data and a second face group contained in the second image data based on the determined storage type, the mapping relation establishing comprising: when the determined storage type of the image is both storing in the local device and storing in the another device, and when the first face data of the image and the second face data of the image contain a same face, detecting whether the first face group corresponding to the same face has a mapping relation by determining whether the second face group corresponding to the same face is mapped to the first face group corresponding to the same face; and in response to detecting that the first face group corresponding to the same face has no mapping relation, establishing a mapping relation between the first face group and the second face group corresponding to the same face; and merging, by the local device, the first image data containing the first face group and the second image data containing the second face group having the mapping relation with each other, so as to synchronize image data between the local device and the another device. acquiring, by a local device, first image data of images stored in the local device and second image data of images stored in another device; comparing, by the local device, the first image data with the second image data to determine a storage type of an image contained in the first image data and/or contained in the second image data by determining whether the image is stored in one, the other or both of the local device and the another device based on a storage path or a message digest contained in the first image data and contained in the second image data, the storage type comprising: both storing in the local device and storing in the another device, or only storing in the local device, or only storing in the another device, wherein the first image data further contains first face data of an image stored in the local device and a first face group corresponding to a face contained in the first face data, the second image data further contains second face data of an image stored in the another device and a second face group corresponding to a face contained in the second face data; establishing, by the local device, a mapping relation between a first face group contained in the first image data and a second face group contained in the second image data based on the determined storage type, the mapping relation establishing comprising: when the determined storage type of the image is both storing in the local device and storing in the another device, and when the first face data of the image and the second face data of the image contain a same face, detecting whether the first face group corresponding to the same face has a mapping relation by determining whether the second face group corresponding to the same face is mapped to the first face group corresponding to the same face; and in response to detecting that the first face group corresponding to the same face has no mapping relation, establishing a mapping relation between the first face group and the second face group corresponding to the same face; and when the determined storage type of the image is both storing in the local device and storing in the another device, and when the first face data of the image and the second face data of the image contain a same face, detecting whether the first face group corresponding to the same face has a mapping relation by determining whether the second face group corresponding to the same face is mapped to the first face group corresponding to the same face; and in response to detecting that the first face group corresponding to the same face has no mapping relation, establishing a mapping relation between the first face group and the second face group corresponding to the same face; and merging, by the local device, the first image data containing the first face group and the second image data containing the second face group having the mapping relation with each other, so as to synchronize image data between the local device and the another device.