  In this article, we take the point of view that the light scalar meson
$a_0(980)$ is a conventional $q\bar{q}$ state, and calculate the coupling
constants $g_{a_0\eta\pi^0}$ and $g_{a_0 \eta'\pi^0}$ with the light-cone QCD
sum rules. The central value of the coupling constant $g_{a_0\eta\pi^0}$ is
consistent with the one extracted from the radiative decay $\phi(1020)\to
a_0(980)\gamma \to \eta \pi^0 \gamma$. The central value and lower bound of the
decay width $\Gamma_{a_{0}\to \eta \pi^0}=127^{+84}_{-48} \rm{MeV} $ are
compatible with the experimental data of the total decay width
$\Gamma_{a_0(980)}=(50-100) \rm{MeV}$ from the Particle Data Group with very
model dependent estimation (the decay width can be much larger), while the
upper bound is too large. We give possible explanation for the discrepancy
between the theoretical calculation and experimental data.
