  We investigate the direct $CP$ violation for the decay process of
$\bar{B}_{s}\rightarrow P(V)\pi^{0}$ (P,V refer to the pseudoscalar meson and
vector meson, respectively) via isospin symmetry breaking effects from the
$\pi^{0}-\eta-\eta'$ mixing mechanism in PQCD factorization approach. Isospin
symmetry breaking arises from the electroweak interaction and the u-d quark
mass difference by the strong interaction which are known to be tiny. However,
we find that isospin symmetry breaking at the leading order shifts the $CP$
violation due to the new strong phases.
