  The trace amplitude method (TAM) provides us a straightforward way to
calculate the helicity amplitudes with massive fermions analytically. In this
work, we review the basic idea of this method, and then discuss how it can be
applied to next-to-leading order (NLO) quantum chromodynamics (QCD)
calculations, which has not been explored before. By analyzing the singularity
structures of both virtual and real corrections, we show that the TAM can be
generalized to NLO QCD calculations straightforwardly, the only caution is that
the unitarity should be guaranteed. We also present a simple example to
demonstrate the application of this method.
