To make new filler for conducting rubber, the sample of perovskite-related ferrite system $Dy_{2-x}Sr_{1+x}Fe_2O_{7-y}$ (x=0.0, 0.5, 1.0, 1.5, and 2.0) were synthesized at 1473K in air. $M{ddot{o}}ssbauer$ spetrum of x=0.0 sample shows typical six line pattern with $M{ddot{o}}ssbauer$ parameters, $I.S=3.6{ imes}10^{-1}mm/sec,;E_Q=-7.0{ imes}10^{-2}mm/sec,;H_{int}=5.19{ imes}10^2;Koe$. In case of x=2.0, the spectrum is composed of single line exhibiting coexistance of $Fe^{3+}(I.S.=3.7{ imes}10^{-1}mm/sec)$ ions and $Fe^{4+}(I.S.=-1.9{ imes}10^{-1}mm/sec)$ ions. With increase in x value electrical conductivity at constant temperature sharply increased and the activation energies decreased from $3.8{ imes}10^{-1};to;1.9{ imes}10^{-1};eV$.