Abstract: Basing on Green-Ampt Model,and taking the small-angle slope made of dry soil that according with Green-Ampt infiltrating model as object,its infiltrating regulation under heavy raining intensity is studied.It puts forward the infiltrating formula including gas pressure making use of Green-Ampt Model,and gets the real infiltrating formulas under the constant raining intensity.Then it combines with the overland flow formulas to get the numerical modeling of infiltration and overland flow under heavy raining intensity.