Abstract: Uncertainties associate with parameter estimation in modeling the water cycle can be reduced to a certain extent by expanding the utilization of modeling information and increasing the amount of data for parameter estimation.This is done through collecting and using the isotopic composition of water within the water cycle in model identifieation.In this study,the isotopic information is used to estimate the steady-state infiltration rate in Philip's two-parameter equation and the estimated parameters are validated through the indoor experimental data.The result shows that the estimated steady-state infiltration rate is in food agreement with the measurement.Analytical previsions of hydrogen and oxygen stable isotopes will have some impact on parameter estimation using isotopic information.