Abstract：The system maintenance becomes more and more notable with the development of system developing and implementing technologies. Particularly, the maintenance problems of the group organization's ERP(Enterprise Resource Planning) system are more distinctive because of its complexity. Up to now, researches have been limited to relational models, maintenance problems of specific systems such as real-time systems or web-based systems, and factors related to the efficiency of maintenance activities such as maintenance men's experiences or the systems' complexity. While few concentrate on ERP systems and even few take care of the maintenance problems of group organizations' ERP system. Through investigating two large group organizations, this paper concludes the characteristics of group organizations and analyzes its factors related to maintenance efficiencies. Further more, it summarizes a relatively suitable maintenance mode for group organizations' ERP systems: the centralized maintenance with self-maintenance and multi-maintenance.