Ceramic samples of La0.1Sr0.9TiO3 are synthesized by conventional solid state reaction technique at 1440℃, 1460℃, 1480℃ and 1500℃, respectively. Their thermoelectric properties are investigated. X-ray diffraction characterization confirms that the main crystal structure is of perovskite. Scanning electron microscope images indicate that all ceramic samples are dense and compact, and that the average grain size increases with the increase of sintering temperature. Electrical resistivity and Seebeck coefficient of samples are measured in the temperature range between room temperature and 800℃. In general, with the increase of sintering temperature, the electrical resistivity first increases, and then decreases. With the increase of sintering temperature, the absolute Seebeck coefficient first increases, and then decreases. A maximal power factor 21 μW·K-2·cm-1 is obtained at 165℃ for the sample sintered at 1480℃ because of its reletivly high absolute Seebeck coefficient and reletively low electrical resistivity.