  In this paper, the twist-3 two parton corrections in charmless $B\to PP$
decays are shown to be factorizable under the QCD factorization approach. The
factorizability of the twist-3 two parton corrections is constructed on the
following findings. Under the energetic meson limit, the pseudoscalar
distribution amplitude for a light pseudoscalar meson is allowed to be
non-constant by the equations of motion for the quark. The non-constant
pseudoscalar distribution amplitude is then used to regularize the end-point
divergences in the hard spectator corrections at twist-3 order. By retaining
the momentum fraction variable of the spectator quark of the $B$ meson in the
propagators, the end-point divergence in the weak annihilation corrections at
twist-3 order is resolved. The factorization of the $O(\alpha_s)$ corrections
under the two parton approximation is shown valid up-to $O(1/m_b)$ . The hard
scattering kernels of order $O(\alpha_s)$ and $O(\Lambda_{QCD}/m_b)$ are
explicitly given and found to be infrared finite. The results are applied for
making predictions for the branching ratios of $B\to \pi K $ decays.
