Abstract: The permeability coefficient of the field surface is the essential parameter for analyzing both the slope stability and the small watershed rainfall yield. A new method and device is described for field measurement of the surface permeability coefficient. The device combines the advantages of a direct rainfall infiltration test and a two-ring infiltration test device to achieve a saturation surface with zero water pressure infiltration measurement of a slope. The permeability of surface soil can be obtained directly by proposed method. Infiltration tests on a mountainous basin are carried out, and the soil permeability and suction are obtained.