Ca3Co4O9 and Ca3-xLaxCo4O9 powders were prepared by sol-gel process. The Ca-Co-O thermoelectric material ceramics were prepared. The ceramics materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The microstructure and thermoelectric properties of ceramics were researched. The results indicate that the crystal of Ca3-xLaxCo4O9 with La adding growth ideally, the material had high density and low pore rate. The Ca3-xLaxCo4O9 ceramics contain directional array plate-shaped grains with layered structure. The thermoelectric properties of Ca3-xLaxCo4O ceramics were excellent. There were high Seebeck coefficient and high electrical conductivity for Ca3-xLaxCo4O9 ceramics. The power factor increased with temperature increasing.