Abstract: In this paper the back-propagation model which is one of the typical artificial neural network models was used to establish the model for forecasting the epidemic trend of the cotton ball rot based on the collected date from sheyang county during the period of 1980 to 1987.Then by using the model the returning forecasting the trends in 1980 to 1987 and the forecasting the trends in 1988 to 1991 were carried out.The results showed that the model can well predict the trend.