Abstract:A new method for the identification of key factors from life table data of insects is proposed, i. e. the analytic method of grey sequence. The method possesses the integral, asymmetric, sequential, dynamic, and simple and convenient merits. It can accurately identify key factors and show the relative importance of other factors, An illustrative study was made with the life table data of Seperda populnea L. Using the life table data of some insects, the grey sequence was compared with other analytic methods of sequence. The result shows that analytic method of grey sequence is correct and. Practicable. The method is a new one for the identification of key factors affecting population dynamics of insect pests.