  Chiral symmetry and its spontaneous breaking play an important role both in
the light hadron and heavy hadron systems. The chiral perturbation theory
($\chi$PT) is the low energy effective field theory of the QCD. In this work,
we shall review the investigations on the chiral corrections to the properties
of the heavy mesons and baryons within the framework of $\chi$PT. We will also
review the scatterings of the light pseudoscalar mesons and heavy hadrons,
through which many new resonances such as the $D_{s0}^\ast(2317)$ could be
understood.
  Moreover, many new hadron states were observed experimentally in the past
decades. A large group of these states is near-threshold resonances, such as
the charged charmoniumlike $Z_c$ and $Z_{cs}$ states, bottomoniumlike $Z_b$
states, hidden-charm pentaquark $P_c$ and $P_{cs}$ states and the doubly
charmed $T_{cc}$ state, etc. They are very good candidates of the loosely bound
molecular states composed of a pair of charmed (bottom) hadrons, which are very
similar to the loosely bound deuteron. The modern nuclear force was built upon
the chiral effective field theory ($\chi$EFT), which is the extension of the
$\chi$PT to the systems with two matter fields. The long-range and
medium-long-range interactions between two nucleons arise from the single- and
double-pion exchange respectively, which are well constrained by the chiral
symmetry and its spontaneous breaking. The short-distance interactions can be
described by the low energy constants. Such a framework works very well for the
nucleon-nucleon scattering and nuclei. In this work, we will perform an
extensive review of the progress on the heavy hadronic molecular states within
the framework of $\chi$EFT. We shall emphasize that the same chiral dynamics
not only govern the nuclei and forms the deuteron, but also dictates the
shallow bound states or resonances composed of two heavy hadrons.
