To make new filler for conducting rubber, the sample of perovskite-related ferrite system Dy₂ _xSr_(1+x)Fe₂O_(7 y) (x=0.0, 0.5, 1.0, 1.5, and 2.0) were synthesized at 1473 K in air. Mo¨ssbauer spetrum of x=0.0 sample shows typical six line pattern with Mo¨ssbauer parameters, I.S.=3.6×10^(-1)㎜/sec, E_Q=-7.0×10^(-2)㎜/sec, H_(int)= 5.19×10² KOe. In case of x=2.0, the spectrum is composed of single line exhibiting coexistence of Fe^(3+)(I.S.=3.7×10^(-1)㎜/sec) ions and Fe^(4+)(I.S.=-1.9×10^(-1)㎜/sec) ions. With increase in x value electrical conductivity at constant temperature sharply increased and the activation energies decreased from 3.8×10^(-1) to 1.9×10^(-1) eV.