Ion beam sputtering was used to deposit Sb 2 Te 3 thin films on BK7 glass substrates at room temperature. The effect of annealing on the thermoelectric properties of the Sb 2 Te 3 thin films was investigated. After the stoichiometric films were annealed at 100°C to 400°C for one hour, the Seebeck coefficient decreases from 190μVK −1 to 106μVK −1 , and the conductivity increases from 1.1×10 2 Scm −1 to 2.01×10 3 Scm −1 . The Power Factor is enhanced greatly from 0.40×10 −3 Wm −1 K −2 to 2.26×10 −3 Wm −1 K −2 after annealing at 400°C. The positive Seebeck coefficient α suggests the films to be p-type. X-ray diffraction (XRD) shows that the major diffraction peaks of the films match those of Sb 2 Te 3 and high crystalline films are achieved after annealing. These results indicate that high-quality Sb 2 Te 3 thin films are achieved and annealing greatly improves the thermoelectric properties of the films.