In the present work,to improve thermoelectric properties,compacts with non-stoichiometric titanium dioxide,TiO_(2-x) prepared by spark plasma sintering(SPS) were reduced by reduction treatment using carbon powders at 1373 K for 0～20 h,which was proposed in the previous work.Microstructures of the compacts were examined.The carrier density and non-stoichiometric number were calculated by using thermogravimetry(TG) while heating an elevated temperature and re-oxidizing TiO_(2-x) in air.Also,the thermoelectric properties of TiO_(2-x)were evaluated to 823 K in air.It is found that compacts obtained by reducing TiO_(2-x) compacts prepared by SPS had a TiO layer with many voids on the outside and non-stoichiometric TiO_(2-x) in the inside.Thickness of the layer increased with the holding time of the reduction treatment.The 2-x was decreased and the carrier density was increased with increasing the holding time of the reduction treatment.The electrical resistivity was reduced considerably than that from SPS.The values of the Seebeck coefficient of the compacts were maintained at large absolute values over 100μV K~(-1) till 823 K.Power factor reached 3×10~(-4) W m~(-1) K~(-2) at 823 K,is larger than that from SPS.The TiO layer did not display obvious influence on thermoelectric properties of TiO_(2-x). In the present work, to improve thermoelectric properties, compacts with non-stoichiometric titanium dioxide, TiO 2 (2-x) prepared by spark plasma sintering (SPS) were reduced by reduction treatment using carbon powders at 1373 K for 0 ~ 20 h, which was proposed in the previous work. Microstructures of the compacts were examined. The carrier density and non-stoichiometric number were calculated by using thermogravimetry (TG) while heating an elevated temperature and re-oxidizing TiO 2 (2-x) in air. Also, the thermoelectric properties of TiO 2 (2-x) were evaluated to 823 K in air. It is found that compacts obtained by reducing TiO 2-x compacts prepared by SPS had a TiO layer with many voids on the outside and non-stoichiometric TiO_ (2-x) in the inside. Thickness of the layer increased with the holding time of the reduction treatment. 2-x was decreased and the carrier density was increased with increasing holding time of the reduction treatment. The electrical resistivity was reduced considerably han that from SPS.The values ​​of the Seebeck coefficient of the compacts were maintained at large absolute values ​​over 100 μV K -1 -1 823 K. Power factor reached 3 × 10 -4 W m -1 K ~ (-2) at 823 K, is larger than that from SPS. The TiO layer did not display obviously influence on thermoelectric properties of TiO_ (2-x).