Abstract: According to characters of the relation between the population dynamics of Dendrolimus punctatus and the related environment and Nicholson-Bailey Model,this paper recommends a timedelay structure and stable control item,and establishes a simulation model of Dendrolimus punctatus population dynamics with difference equation methods.Based on the model,the mechanism of the population dynamics is discussed. Following results are obtained:the stronger the ability for the pest control by forest itself,the lower the equilibrium position of the population is and the better the stability is;the larger the inner growth rate of the population,the higher the equilibrium position is and the worse the stability is.

Key words: Dendrolimus punctatus, Population dynamics, Equilibrium point, Simulation