Abstract: In this paper, according to variational principle, eqs.（19）and （20） are proposed to compute head distribution and seepage discharge by the finite element method, which satisfy the general definite solution problem eq. （1） for unconfined three-dimensional unsteady seepage of Darcy's law. It is verified that they are an available numerical approach for analyzing three-dimensional unsteady seepage flow problem with free surface through the computation of a pumping well of unconfined unsteady seepage.