Abstract: Agrometeorological Forecast System plays an important role in making agricultural management decisions. This paper presents the general design of Agrometeorological Forecast System and mainly describes the methods of small error probability (P. C)test and fuzzy decision applied by the forecast system. It was verified that the forecast accuracy was enhanced in large scale, the involved decision-making factors were added and the quantitative decision-making basis was provided. So the general decision-making would be greatly improved by the application of these methods. Practical application of this system for several years in agricultural management increased the production benefits and economic benefits distinctly.