  Based on an approximate six-quark operator effective Hamiltonian from
perturbative QCD, we present a systematical study of charmless $B \to PP, PV,
VV$ decays ($P$ and $V$ denoting pseudoscalar and vector mesons, respectively).
The calculation of the relevant hard-scattering kernels is completed, the
resulting transition form factors are consistent with the results of QCD sum
rule calculation. Important classes of power corrections include
"chirally-enhanced" terms, vertex corrections and weak annihilation
contributions with non-trivial strong phase. With these considerations,
predictions are presented for the branching ratios and CP asymmetries of
B-meson decays into PP, PV and VV final states, and also for the corresponding
polarization observables in VV final states. Several decay modes and
observables, which are of particular interest phenomenologically, are discussed
in detail, including the effect of annihilation amplitude with strong phase,
the $\pi\pi$, $\pi K$ and $\pi \rho$ systems, the longitudinal polarization
fraction $f_L$ in $\rho K^*$ and $\phi K^*$ systems and so on. It is observed
that predictions in our framework generally agree with the current experimental
data.
