Abstract: The governing equation of water-air phase flow is the best one,and established by the two fluid volume-averaged momentum and continuity equations based on seepage mechanics and the optimization theory of parameter inversion.The constitutive relationships of permeability-saturation-pressure controlling multiphase flow is given.The optimal estimation values are obtained by adopting the constrained variable metric method to inverse the parameters.The results show that the optimized values by the numerical method in this paper is in good agreement with the experimental data,and the comparison analysis validates the reliability and practicability of the numerical model,which deals with the sensitivity of the values to the initial conditions.The uniqueness and stability analysis indicates that the inverse model is well posed,and that the numerical model provides sufficient information for the successful application of the parameter-estimating approach.The numerical experimental is completed by this method,using the numerous initial values to meet the practical project.It not only supplies the foundations to the numerical calculation of the contaminant transport in unsaturated zone,analyzes well the test data in the process of oil gas reservoir exploitation,the landfill gas release and the contamination remediation of the volatile organic compounds,but also provides the theoretical basis for determining the parameter of the permeability-saturation pressure.