Abstract:The development of three-dimensional finite element method,which can be applied to the immiscible contaminant transport problems in the underground flows,for two-phase flow in porous media is developed. The fundamental theory and numerical discretization formulations are elaborated. The numerical difficulty brought about by the distinct nonlinearity of the temporal evolvement of saturation-dependent variables is overcome by the mixed-form formulation. The effectiveness of simultaneous solution(SS) method and its efficiency improvement are explained. Finally,two computational examples are given for verification of the correctness and demonstration of the preliminary applicability.