Abstract: The field census data of aphid population in Zhengding county and Baoding area, Hfibei province, was statistically analysed by use of the principle of stepwise regression and stepwise discrimination and the method of representative elements of clustering analysis for selecting the independent variables, and the four-grade discrimination formula for reporting the aphid disaster degree and the long- term prediction models for reporting the highest aphid density in May were established.The aphid population at the date of heading could be predicted two months ahead of time.In order to determine the reliable control date, the growth regularity of aphid population in May was studied.The results showed that the aphid population growth curve assumed a "S" type, and the logistic curve equation was Y =7764.519/1+2843.669e-1.3202x.The above results can provide basis for controlling aphid in winter wheat field.

Key words: Wheat aphid, Representative elements for clustering analysis, Statistical analysis, Computer simulation, Prediction model