  In the framework of topcolor-assisted technicolor(TC2) models, we calculate
the contributions of flavor changing scalar couplings involved the neutral
top-pion $\pi_{t}^{0}$ and top-Higgs $h_{t}^{0}$ to the branching ratio
$B_{r}(t\longrightarrow cg)$. We find that the value of $B_{r}(t\longrightarrow
cg)$ can reach $ 1\times10^{-3}$ with reasonable values of the parameters in
TC2 models, which may be testable in the future experiments.
