In view of the fact that the traditional Green-Ampt infiltration model ignores the influence of slope angle and unsaturated zone of soil on the rainfall infiltration of slope, the gradient of infiltration potential energy of soil was modified by using the slope angle, and the soil was divided into saturated layer, transition layer and non humid layer during infiltration. Then a new model based on stratified assumption considering inclination was established. The relationship between infiltration depth and rainfall duration was ascertained and the new model was compared with the traditional GA model through an infiltration example. The results show that the surface runoff initiation time and the relationship between wetting front depth and rainfall duration predicted by the new model are closer to the measured values than those by the GA model. In the stage of free infiltration, the wetting front depth of the new model is the same as that of GA model, but the infiltration rate of the new model is lower than that of GA model. In the stage of ponding infiltration, the wetting front depth and infiltration rate of the new model are higher than those of GA model, and the difference of wetting front depth increases gradually with the increase of rainfall duration, while the change of difference between infiltration rates shows the opposite trend. According to the new model, the influence of slope inclination and rainfall intensity on rainfall infiltration is analyzed. It is found that the rainfall duration required for rainwater infiltration into the same depth of slope increases with the increasing slope inclination or the decreasing rainfall intensity, which is especially obvious when the inclination is more than 60° or the rain intensity is less than 20 mm/h.