Two kinds of nanosized indium-tin-oxide (ITO) powders were prepared by heating the ITO precursors at 600 and 1000 oC respectively. The compacts were obtained by press molding of the powders. Then ITO targets were prepared by sintering the compacts at 400-1550 oC in oxygen atmosphere. The powders and the targets were characterized. The grain growth during sintering, the relationship between the targets’ microstructure and the sintering temperature, and the oxygen content of the targets were investigated. The results show that powders prepared by heating the ITO precursors at 600 oC (600 oC ITO powder) are single phase, and their grain size is 15 nm. Powders prepared by heating the ITO precursors at 1000 oC (1000 oC ITO powder) contain a little SnO2, and the grain size is 28 nm. 1000 oC ITO powders exhibit better dispersivity and keep higher crystallization degree. The sintering process of these two kinds of ITO powders corresponds with Coble Solid Phase Sintering process. When the sintering temperature is 1550 oC, crystal growth steps similar to the steps appearing in the two-dimensional nucleation growth can be observed. ITO targets’ density increases as the temperature rises and holding time extends. The density of ITO targets made from 1000 oC ITO powders is higher than that of the targets made from 600 oC ITO powders. This phenomenon indicates that targets’ densification is determined by the degree of agglomeration and the size of agglomerates. Both types of targets contain less oxygen than the theoretical value. And the oxygen content of targets made from 1000 oC ITO powders are higher than that of targets made from 600 oC ITO powders.