A p-version adaptive error estimator for 3D steady seepage analysis is developed. By the fully exploring of the advantages of less preprocessing
higher accuracy and rapid convergence of p-version FEM
a serial of technical problems for solving 3D steady seepage problem by p-version FEM are studied; and an adaptive strategy is put forward. The influences on free surface caused by order of elements and mesh size are analyzed. An example shows that the 3D p-version FEM proposed is feasible for seepage analysis.