Water quality model is a key tool of water polluter transport and transform simulation. It is widely used in the field of water environment protection and water pollution prevention and cure. According to standard J2EE, satisfying expandability, maintainability of software and high rate of code reuse, taking application frame of middleware technology style as base, zero-water quality model as represent, adopting MVC software design model, water quality forecasting middleware is realized, water quality forecasting system that about Web is built,and the WebGIS technology visualization water quality simulation result is used. This system shortens model building period and enhances the model running efficiency.