Abstract: The modified BaTiO₃ ceramics were prepared by two method s:liquid doping and gaspenetra-tion,and the effects of La doping and La penetration on structure and electric characteristics of BaTiO₃ ceramics were studied.The BaTiO₃ ceramic doped with La³⁺ was prepared by Sol-Gelmethod.The resistivity of BaTiO₃ ceramic doped with La³⁺ decreasesobviously,and when La³⁺ content is 0.003 mol,the resistivity becomes the smallest,which changes from 4.0×10¹² Ω·m to 3.0×10⁶ Ω·m.The BaTiO₃ ceramic penetrated with La³⁺ was prepared by gaspenetration method under different tempera-tures.The resistivity of BaTiO₃ ceramic spenetrated with La³⁺ decreasesobviously too,and when the La³⁺ content in the solvent is 0.02, the penetration temperature is 920℃and the penetration time is 4h,the resistivity decreasesto the smallest,value which is 8.2×10⁴ Ω·m.The grain resistance of BaTiO₃ ceramic doped with La³⁺ exhibits NTC effect,but the grain boundary resistance shows PTC effect,and the grain boundary resistance is larger than the grain resistance,so the PTC effect originates from the grain boundary.But the grain resistance of BaTiO₃ ceramic penetrated with La³⁺ exhibits an obvious PTC effect with the change of tempera ture, the grain boundary resistancedecreases rapidly with increase of temperature,and the changerule of the total resistance is similar to that of the grain boundary, the PTC effect disappears.Through XRD analyses,it show that the crystal type of BaTiO₃ ceramic doped with La³⁺ istetragonal,the re is nonew peaks a ppear.However,it is found that in the XRD pattern of BaTiO₃ ceramic penetrated with La³⁺,the re are characteristic peaks of BaTiO₃, La₂C₂O₂ and Ba₅ La₄ Ti₈ O₂₇.It shows that the La enter in to the Ba TiO₃ ceramics during gaspenetration and the complex reactionstake place toform somenew compounds,which leadsto ra pid increase of con-ductivity.It is further confirmed by SEM analyses that the ceramics change to more fine,evengrained structuredue to the La entering in to the BaTiO₃ ceramics,and formation of new phases as center of crystallization.