The present disclosure provides a composite anode unit, comprising: a metal core rod; a metal layer coated on the metal core, wherein the metal layer is lead or lead alloy; a conductive ceramic layer coated on the metal layer, wherein the conductive ceramic layer comprises β-PbO2—Al2O3 composite oxide; an active ceramic layer is coated on the conductive ceramic layer, wherein the active ceramic layer comprises γ-MnO2—Ti4O7 composite oxide. Methods for preparing the composite anode unit and an anode plate made from the composite anode unit are also provided.