  In this work, we analyse the CP-averaged branching ratios and direct
CP-violating asymmetries of the four-body decays B_{S} \rightarrow \pi\pi\pi\pi
decay from the S-wave resonances, f_{0}(980) and f_{0}(500) and P-wave
resonances, \rho(770) by introducing the S-wave and P-wave \pi\pi distribution
amplitudes within the framework of the perturbative QCD approach. We also
calculate branching ratios of the two-body decays
B^{0}_{S}\rightarrow\rho^{0}\rho^{0}, B^{0}_{S}\rightarrow\rho^{+}\rho^{-} from
the corresponding quasi-two-body decays models and compare our results with
those obtained in previous perturbative QCD approach, QCD factorization
approach and FAT approach, it is found that the predictions are consistent with
present data within errors. The branching ratios of our calculations for the
four-body decays B_{S}\rightarrow \pi\pi\pi\pi are at the order of the 10^{-7}.
For the CP-violating asymmetries, we found that CP-violating asymmetry can be
enhanced largely by the \rho-\omega mixing resonances when \pi\pi pairs masses
are in the vicinity of \omega resonance.
