  The complete next-to-leading order (NLO) QCD corrections to charged Higgs
boson associated production with top quark through $b g \to tH^{-}$ at the CERN
Large Hadron Collider are calculated in the minimal supersymmetric standard
model (MSSM) and two-Higgs-doublet model in the $\bar{MS}$ scheme. The NLO QCD
corrections can reduce the scale dependence of the leading order (LO) cross
section. The K-factor (defined as the ratio of the NLO cross section to the LO
one) does not depend on $\tan\beta$ if the same quark running masses are used
in the NLO and LO cross sections, and varies roughly from $\sim 1.6$ to $\sim
1.8$ when charged Higgs boson mass increases from 200 GeV to 1000 GeV.
