Abstract: In order to measure the soil permeability coefficient accurately in term of energy, the distribution law of pressure potential in saturated soil was analyzed based on two-ring infiltration method and cutting ring method, and the two calculation methods were researched on the basis of Darcy’s Law. The results showed that the permeability coefficient was larger than the stable infiltration rate determined by using two-ring infiltration method. The distribution law of pressure potential in saturated soil using two-ring infiltration method to determine the permeability coefficient was different to that using cutting ring method. So the calculation equations of permeability coefficient that correspond to the two kinds of determination methods were different.