Sn-doped 111203 (ITO) nanopowders were prepared in ethanol solvent by solvothermal process.The effects of the solvothermal temperature,coprecipitation pH value and SnO2 content on the products phase and microwave absorption were investigated by X-ray diffractometry and microwave reflectance.ITO nanopowders with cubic structure can be respectively prepared at 250 and 270 ℃ for 6 h.The prepared product is InOOH or the mixture of InOOH and In3Sn4O12 when the solvothermal temperature is below 250℃.With rising solvothermal temperature and prolonging time,the absorption of the ITO powders gradually decreases.The products are ITO nanopowders by coprecipitating at pH=9 or 11,but ITO powders with Sn3O4 at pH=6.The absorption of powders prepared at pH=6 is better than that at any other pH value.The products are all ITO nanopowders and crystal size reduces with increasing SnO2 content.The microwave absorption of ITO nanopowders with SnO2 content of 8% (mass fraction)is the best among samples with different SnO2 contents.