  In this paper we present a detailed formulation for a recently proposed
effective field theory to describe the nonperturbative QCD dynamics of heavy
mesons. This effective theory incorporates with heavy quark symmetry (HQS) and
the heavy quark effective theory (HQET). Heavy mesons in this theory are
constructed as composite particles of a heavy quark bounded with the light
degrees of freedom. The heavy meson properties in the heavy quark limit and the
$1/m_Q$ corrections can then be explicitly evaluated from this effective
theory. All the basic parameters of the HQET, namely, the heavy quark mass
$m_Q$, the heavy meson residual mass $\overline{\Lambda}$, and the HQS breaking
mass parameters $\lambda_1$ and $\lambda_2$, are consistently determined.
$\lambda_1$ is found to be small due to a large cancellation between the heavy
quark kinetic energy and the chromo-electric interaction between the heavy
quark and light degrees of freedom. We also evaluate the Isgur-Wise function,
the decay constant, and the axial-vector coupling constant of heavy mesons.
