The characteristic of calcined BaTiO3 powder and sintered PTC ceramics was investigated varing with calcination temperature and time of BaTiO(C2O4)2.4H2O synthesized from BaCl2.2H2O, TiCl4, oxalic acid and ethanol by oxalic acid method. When the particle size was less than 0.1 ${mu}{ extrm}{m}$ by controlling calcination temperature and time, the resistance at room temperature was measured very high (above M{{{{ OMEGA }}). However, when the calcined particle sizes ranged from 0.2 to 0.3 ${mu}{ extrm}{m}$, the resistance was 100 {{{{ OMEGA }} (After sintering, the grain size was 10~30 ${mu}{ extrm}{m}$ homogeneously with the addition of dopant in sintering, the resistivity, resistance, $alpha$ value and jumped to were 110{{{{ OMEGA }}.cm, 24$^{circ}C$/% and 106{{{{ OMEGA }}, respectively.