Effects of electric-field-induced lattice distortion on the polarization and strain were investigated in Pb(Mg₁3/Nb₂3)O₃ relaxor ferroelectric ceramics in the temperature range of -50℃∼90℃. The ratio of residual strain and polarization (S_r/P_r rarely depends on the temperature. However, the ratio of the electric field included strain and polarization (S_induced/P_induced) increased as the temperature decreases below phase transition temperature. To explain these experimental results, a simple rigid ion model concentrating on only Bo₆ octahedron was suggested.