Abstract: The aircraft process data is important to the aircraft assemble, and the computer-aided process planning (CAPP) system is an important information system for the assemble technical design. For the reliable backup of the process data, the relevant backup mode for the CAPP system is studied. According to the feature of the aircraft process data and the CAPP, an improved paaern of the parent-child strategy is proposed, to make a periodical full backup, and to calculate the period of the medium protection. The backup system uses the LAN-based infrastructure, with the rational time strategy, and has achieved a good result.