Abstract: In order to study the relationship between the life habit of pine caterpillar and environment, forecast and control pine caterpillars disasters more effectively, the author used the relationship between the meteorological factors and occurrence period of pine caterpillar, to forecast the beginning stage of pine caterpillar with stage distance method and multivariate regression analysis method. The results showed that: by studying the relationship between a single meteorological element and occurrence period of pine caterpillar, temperature was the main factor affecting the occurrence of pine caterpillar in the larvae on the tree to eclosion beginning period and rainfall was the main factor affecting it in the larvae climbing down the tree. By using stage distance method, forecasting the occurrence period of pine caterpillar within 6 days of deviation ratio was 72.5% . According to the relationship between meteorological elements and occurrence period of pine caterpillar, sunshine hours and daily range were the main factors affecting the occurrence of pine caterpillar in the larvae on the tree to eclosion beginning period, temperature and rainfall were the main factors affecting it in the larvae climbing down the tree, and by using multivariate regression analysis method, forecasting the occurrence period of pine caterpillar within 6 days of deviation ratio was 67.5%.