In order to forecast the occurrence area of Dendrolimus by using meteorological factors, the author analyzed the relationships between meteorological factors and occurrence area of Dendrolimus with the data from 1983 to 2008 in Fuxin County, Liaoning. The occurrence area of Dendrolimus was simulated and predict on the selected meteorological factors as forecast factors, using multiple element regression and artificial neural network methods. The results showed that: 5 meteorological factors were significantly correlated with the occurrence area, including the mean minimum temperature of preceding December, the mean relative humidity of preceding November, the precipitation of preceding September, the precipitation of current February and current March. The simulation and prediction accuracy rate of the artificial neural network method was better than that of the multiple element regression method, the multiple element regression method reached over 58.2% while the artificial neural network method reached over 83.6%. The artificial neural network method was more appropriate for the occurrence area forecast of Dendrolimus in Liaoning.