Abstract: This is one of the serial papers on the Computer-aided forecasting network for rice pests and diseases. The forecast entity model for the rice pests and diseases was analysed. The layer division of the network, the confugurations of the conputer hardware and the communication devices were established. Through the analyse of entity model of the data base for the pests and diseases, the designation principle, the designing method for the structures and files of the data base were worked out. The functions of the software of the network were divided into four parts. (1) the data base management, (2) the forecasting analysis system, (3) the forecasting consult system and (4) the communication service system. The network has been successfully put into agricultural production in Nan Ping Prefecture, Fujia Provice in 1991.