The occurrence degree of Mythimna separata Walker was divided into three grades（namely mild, moderate and severe occurrence）, and related meteorological conditions divided into several grades according to the life habit of Mythimna separata Walker during 1999-2015, then a correlation analysis on the occurrence degree of Mythimna separata Walker and related meteorological conditions was made in the paper. It was found out that the occurrence degree of Mythimna separata Walker was good related to the precipitation during late May to early June.Due to the fact that Mythimna separata Walker is a dangerous species formed by the migrating adult, the occurrence degree of Mythimna separata Walker was also closely related to the pheromone catches during late May to earlyJune. The meteorological forecast model for the occurrence degree of Mythimna separata Walker in Tonghua was established by using the multivariate regression statistical method, and the model has a multiple correlation coefficient of 0.735, meanwhile the simulation precision of the model was up to 82.4% at the 0.05 significance level. Using the data of 2016 to test the model, the test results were all correct. Therefore the forecast model has a certain level of us-ability, and it can satisfy the requirement of forecast service.