络的75%。A forecast system of diseases and pests for apple orchards was developed by using MVC structure with Java support based on ArcIMS. The forecast model, which could predicate 20 kinds of the diseases and pests, was integrated with spatial analyses of GIS by dynamic data exchange (DDE). The system can be applied to analyze spatially and temporally, forecast the diseases and pests, and promulgate the information with WebGIS. The forecasting of the regions and infection tendency of diseases and pests can be revealed with several patterns, such as map filled with different colors, topic graph, data table, text, or figure. Additionally, for instance of Tetranychus Viennensis in apple orchards, the predicting model constructed with radial basis function neural network (RBFNN) was purposed in this paper, and the predicting results were compared with those of backpropagation (BP) neural network model. 