The paper mainly deals with the analysis of influential factors and the development of the forecasting model of soil erosion in Taihu valley. The influential factors such as climate, soil types, geologic conditions, vegetation coverage and land-usage were qualitatively and quantitatively analyzed and summarized according to the principles of soil erosion.A mathematical model of soil erosion was developed in a small scale for predicting the happening and development of soil erosion by taking slope position, slope form, slope degrees, soil depth, vegetation coverage and land-usage as independent variables and the module of soil erosion as a dependent on the basis of regression analysis. A forecasting model of soil erosion in Taihu valley developed is as follows:Y k=B 0+ΣP1+1j=1Σm1i=1B(j,i)φ k(j,i)+Σpj=p1+1B(j)X kj 