A method of backing up and recovering data in a data processing system is disclosed. The method includes selecting files to be backed up, and determining where to save selected files; loading a project file to manage backup information on the selected file; building a baseline in the project file; backing up the selected files with the baseline, and updating a backup file DB including information on storage addresses where the selected files are saved; and completing data backup by saving an updated backup file database (DB) in the project file. With this configuration, the present invention provides a method for backing up and recovering data by using a baseline, in which a baseline is built in a project file whenever data backup is performed, so that not only is the data easily backed-up and recovered even if the data backup is repeatedly performed and an amount of data is managed, but also a space of a storage unit that is used to store the backup files is efficiently used.