Polymer/perovskite manganese oxide (epoxy resin/La_0.8Sr_0.2MnO₃) composites are prepared using bonded method. There is no reaction between La_0.8Sr_0.2MnO₃ and the polymer. The nonlinear current–voltage property is significantly affected by the content of polymer. The resistivity and nonlinear coefficient increase with the increase of polymer content. The resistivity of the composites is 5–9 orders of magnitude higher than that of the sintering ceramics. The nonlinear electrical behavior is an intrinsic property. Compared with conventional sintered ceramic varistors, the polymer/manganese oxide composite varistors have greater nonlinear coefficient above 45.