Abstract: In this paper, according to their difference in "physical" meaning , twodimensional phreatic flow equation, which has been transformed, is devided into two parts──advection and dispersion by the splitting method. For the former, alternating direction finite difference method will be used and for the faller, it is resolved by altemating direction Picard iteration, therefore, the aim of computing the solution of whole problem will be reached. At last, the validitt of the algorithms is proved by the numerical example . The comparison of the proposed method with the conventional finite difference (linearized) is made. The results show that the precision of calculationby the method proposed in this paper is better than the conyentional methods.