In the seepage forward modeling of earth-rock dams, the study of seepage field in saturated area alone can not fully reflect the underground seepage state of earth-rock dams, the unsaturated seepage field is just as important. Here, the saturated-unsaturated seepage field is solved by the element-free Galerkin method. Firstly, the seepage equation and boundary conditions are derived from Darcy’s law, and the element-free Galerkin method is derived in detail. The essence of Galerkin method is to construct a form function by moving least squares method, and to calculate the boundary conditions by penalty function.Then, the accuracy and effectiveness of the method are proved by comparing the results of the saturated seepage field and the saturated-unsaturated seepage field calculated by GeoStudio. Finally, the distribution of zero pressure line, water head value, pore pressure and water content in the dam body is studied by different homogeneous and heterogeneous models. The element-free Galerkin method only requires nodes to achieve accurate approximation of the whole domain seepage field, which eliminates the dependence on grid cells. Compared with other numerical methods, this method has the advantages of simple early processing data and high precision, so it is more suitable for the complex forward simulation of the stable saturated-unsaturated seepage field.