Abstract: It is an important basis for evaluating the rational level of urban development to determine reasonably scale of urban land use.This paper chooses the important influence factors of developed areas：Annual GDP，the gross output of industry and agriculture，total population etc.，and makes use of grey GM（1，N），BP Neural Network to construct forecasting models，respectively，as well as analyzes and makes comparison of the advantages and the disadvantages of each model.This paper proposes the combination forecasting model by using standard variance to allocate the weight.The result of practical example shows that the forecasting accuracy of combining forecasting model is better than that of the single model，which is a beneficial exploration for the forecasting method of developed areas.