  We study the signal of dark matter and photon associated production induced
by the vector and axial-vector operators at the LHC, including the QCD
next-to-leading order (NLO) effects. We find that the QCD NLO corrections
reduce the dependence of the total cross sections on the factorization and
renormalization scales, and the $K$ factors increase with the increasing of the
dark matter mass, which can be as large as about 1.3 for both the vector and
axial-vector operators. Using our QCD NLO results, we improve the constraints
on the new physics scale from the results of the recent CMS experiment.
Moreover, we show the Monte Carlo simulation results for detecting the
$\gamma+\Slash{E}_{T}$ signal at the QCD NLO level, and present the integrated
luminosity needed for a $5\sigma$ discovery at the 14 TeV LHC . If the signal
is not observed, the lower limit on the new physics scale can be set.
