We study the low energy pion-hyperon interaction considering effective non-linear chiral invariant Lagrangians including pions, ρ-mesons, σ-mesons, hyperons and corresponding resonances. Then we calculate the S-and P -wave phaseshifts, total cross sections, angular distributions and polarizations for the momentum in the center-of-mass frame up to k = 400 MeV. With these results we discuss the CP violation in the Ξ → Λπ and Ω → Ξπ weak decays.