  The multipole moments method is not only an aid to understand the deformation
of the space-time, but also an effective tool to solve the approximate
solutions of the Einstein field equation. However, The usual multipole moments
are recursively defined by a sequence of symmetric and trace-free tensors,
which are inconvenient for practical resolution. In this paper, we develop a
simple procedure to generate the series solutions, and propose a method to
identify the free parameters by taking the Schwarzschild metric as a standard
ruler. Some well known examples are analyzed and compared with the series
solutions.
