  We calculate the two-loop mixed QCD$\otimes$EW corrections for the charged
Higgs boson pair production within the framework of four types of Two Higgs
Doublet Models (THDMs) with the $Z_2$ symmetry. We analyze in detail the
dependences of our results on physical parameters, including the charged Higgs
mass, $\tan\beta$, the scattering angle, and the colliding energy. It is
noticeable that the mixed QCD$\otimes$EW relative correction is independent of
the scattering angle due to the topology of Feynman diagrams at
$O(\alpha\alpha_s)$. Numerical results in most allowed regions of four types of
THDMs are provided in the density plots on the $m_{H^{\pm}}$-$\tan\beta$ plane.
For type-I and type-X, the mixed QCD$\otimes$EW relative correction varies
slightly near $1\%$ except in the vicinity of resonance. For type-II and
type-Y, the corrections increase consistently in large $\tan\beta$ region and
reach up to $11.5\%$ at $\tan\beta = 50$. We also compute the $O(\alpha)$
corrections to obtain the corrected cross section up to $O(\alpha\alpha_s)$.
The numerical results show that the corrected cross section can be larger than
$80\ \mathrm{fb}$ in some parameter space region for type-I and type-X THDMs.
