Indium tin oxide (ITO) nanopowders with high crystalline were synthesized by a simple solvothermal method with isopropanol as the selected solvent. X-ray diffraction was employed to characterize the crystal structure and crystalline size while the effect of the reaction time on morphologies was studied by FE-SEM. The results revealed that, with the increase of solvothermal time, the morphologies were evolved gradually from porous plates with high specific surface area to rods with narrow diameter distribution. The solvothermal time has little effect on crystalline size, which is 18nm approximately for all the samples. With the increase of solvothermal time, the electric conductivity decreases slightly first and then increases greatly. The possible mechanisms for the effect of solvothermal time on ITO powder morphologies and electric conductivity are proposed.