  We derive the mass correction lagrangian of the heavy meson effective theory
by using the projection operator method. The next leading order of the mass
correction and the first order of the chiral expansion are given explicitely.We
also consider the mass correction weak lagrangian of the heavy mesons. Finally,
we give the $\it{D}^{*+}\to \it{D}^o \pi^{+}$ decay.
