This paper discusses a new method for designing and implementing a management system based on graphical variable for stored grain protection. The graphical variable provides more direct information relevant to stored grain state for the users, so that the management of stored grain becomes easier. Otherwise, the method makes also use of graphical variable predict temperature and moisture of stored grain, through simulation operation of management model in a geographic information system, so as to implement scientific management for a number of stored grains over large geographic region. Our experiences have shown that the method not only increases estimation precision for temperature and moisture of stored grain but also decreases computation expense and provides more information relevant to stored grain for users.