Soil water dynamics is one of the important indicators of reclaimed land quality.This paper is concerned about water dynamics in overlying soil with filling layers of different porosities by simulation experiment.Results indicate that water loss is faster when the filling layer porosity is slightly less than that of overlying soil.On the contrary,water loss is positively related to porosity when the filling layer porosity is greater than that of overlying soil.So,in order to keep more water in overlying soil in filling reclamation,filling layer porosity should be designed according to the porosity of overlying soil.