This paper presents that the estimation processes of the dangerous degree of debris flow gulleies determined by the aerial remote sensing, the classified criteria of dangerous degree against the railway and the zoning principles of developmantal degree. The estimation factors are proposed for the image indices of each criterion, which would affect the formation of debris flow gulleies.The developmental factors are concluded into ten indices,marking the points respectively. According to the sum of marking points, the dangerous degree of debris flow gulleies are estimated synthetically. The developmental degree zoning of debris flow gulleies is basically dependent upon the combination of topography, geomorphology and geological conditions. Examples of application are shown.