Thermoelectric materials, which can realize direct conversion between thermal energy and electricity by “Seebeck effect” and “Peltier effect”, are attracting increasing attentions for their potential applications in waste heat recycling. And transition metal oxide (TMO) materials are raising great attentions in high temperature applications based on their better chemical/thermal stability, low toxicity and low fabrication cost over the traditional heavy-metal-based materials. We fabricate high quality TMO-based thin films to explore their intrinsic thermoelectric properties. By the two-dimensional enhancement effect in Seebeck coefficient and thermal conductivity reduction effect by heavy element substitution and boundary scattering, we are trying to develop high performance oxide based thermoelectric materials towards the practical applications, such as flexible thin film thermoelectric devices.