With the computer and the rapid development of information technology, The plant disease intelligence diagnosis and the plant disease early warning network is possible. In this paper, relying on the Internet, the realization of intelligent online plant disease diagnosis, early warning, prevention and other information query and forecasting capabilities. The database base on Internet-based wide area network environment and the help of webGIS technology, including diagnostic module, check module and the prediction module. The intelligent prognosis is tested to the extent and happening of plant diseases, for example, Wheat, cotton, tomatoes and other 12 kinds of plant diseases, and epidemic curve is given. To disease diagnosis and prediction of the professional, technical problems become easy, for the effective control of plant diseases, provide a reference.