  The decays $\eta'\to3\pi^{0}$ and $\pi^{0}\pi^{+}\pi^{-}$ were consider in
isobar model approach. Branching ratio and Dalitz-plot shape of the decay
$\eta'\to3\pi^{0}$ can be explain by $a0$- and $\sigma$-meson contributions.
The $\sigma$ meson term is needed for the Dalitz-plot distribution
reconstruction. The branching ratio of the decay $\eta'\to
\pi^{0}\pi^{+}\pi^{-}$ can be calculated in the same isobar framework. The
prediction for the Dalitz-plot of this decay is shown which strongly dependents
from model parameters.
