A method for restoring backup data in an electronic system is provided. The method provides a backup data file, and the backup data file includes at least one record of application data. Then, an application program corresponding to the application data is searched within a registry of the electronic system. If it is found, the application data is restored; otherwise, the application data is not restored. The present invention further provides a method for restoring backup data in a mobile system. The method provides a backup data file, and the backup data file includes a self-restore program. Then, the self-restore program is performed in the mobile device to restore data. Therefore, the present invention can restore data to the mobile device without having to install additional restore program.