  We present the theoretical predictions including the complete next-to-leading
order (NLO) QCD corrections to the top-quark pair production in association
with a photon at the LHC with center-of-mass system energy of $7 {\rm TeV}$.
The uncertainties of the leading order (LO) and NLO QCD corrected cross
sections due to the renormalization/factorization scale, and the distributions
of the transverse momenta of final top-quark and photon are studied. Moreover,
we provide the numerical results of the LO, NLO QCD corrected cross sections
and the corresponding $K$-factors with different photon transverse momentum
cuts. We also discuss the impact of QCD corrections to the \ppttga in case of
there existing the exotic top-quark with an electric charge of $-4e/3$ at the
$7 {\rm TeV}$ LHC.
