  In this paper we construct a covariant light-front model of heavy mesons
within the framework of heavy quark effective theory (HQET). The covariant
model consists of the light-front heavy meson bound states constructed in the
heavy quark limit with heavy quark symmetry and heavy quark effective theory as
its basis. Within this model, the Isgur-Wise function and decay constants in
the infinite quark mass limit can be evaluated in a very simple and the most
general way. The results are ensured to be consistent with heavy quark
symmetry. From the heavy-quark-limit bound states, we can further develop a
systematic approach to calculate $1/m_Q$ corrections from the $1/m_Q$ expansion
of QCD. This covariant model can serve as a quasi-first-principles description
of heavy meson dynamics, namely, a phenomenological covariant bound state in
the heavy quark limit which is consistent with heavy quark symmetry, plus a
reliable first-principles computation of the $1/m_Q$ corrections in HQET in
terms of the $1/m_Q$ expansion of the fundamental QCD theory.
