  We give a simple and straightforward procedure of how to construct an
effective meson Lagrangian from QCD Lagrangian. We integrate the methods of
Gasser, Leutwyler, Alkofer and Reinhardt and use the derivative expansion
scheme to derive the low energy effective Lagrangian for meson fields to
$O(p^4)$. In this paper, why the meson particle can be treated as the goldstone
mode is very clear. In our calculation the result in $O(p^2)$ is the same as in
the chiral perturbation theory, but the result in $O(p^4)$ is different from
that in literature. We will discuss the discrepancies and give some remarks on
our result.
