Abstract: In order to find out the law of the growth and decline of D.puntatus Walk. and develop a mathematical forecast model, the writers collected the 17 years' historical material of D. puntatus Walk. And the meteorological factors at Lianjiang County in Fujian Province. Twelve main factors were selected and then graded. The calculation method of probability regression in the theory of quantization was used for developing the mathematical forecast model. With this model for forecasting 100% accuracy can be achieved. The predictions of the degree of harmness of this insect in 1978,1979 and 1980 were successful.