PTCR ceramic samples of two systems, Bi4Ti3-xNbxO12+x/2(BTNO, 0≤x≤0.01) and Bi4Ti3O12 + (1-z)BaTi1-xNbxO3+x/2+2.0mol%TiO2 (BTO+(1-z)BTNO, 0≤x≤0.01, 0≤z≤1.0), were prepared by mixed oxide method. The properties of the sapmples were characterized by XRD, AFM and electrical properties testing. The results showed that single BaBi4Ti4O15 was obtained when x=0.05 and z=0.5. The roomtemperature resistivity of BTO+(1-z)BTNO ceramic sintered in air was 102-1045·cm. The minimum resistivity occurred at Nb content of about 0.3mol%.