Hexagonal-phase indium tin oxide nanoparticle (h-ITO NP) is a high-temperature and high-pressure phase, and its preparation is more difficult than the cubic one. In this work, low-resistivity and single hexagonal-phase ITO NPs were synthesized through a binary solvothermal method of deionized water (DI water) and glycerol (GL) at relatively mild conditions combined with post-heat treatment. The effects of experimental parameters such as the volume ratios of DI water and GL, reaction time and temperature on the phase, morphology as well as electrical resistivity of h-ITO NPs were explored systematically. The results showed that the reaction time can be as short as 30 min when the single hexagonal-phase ITO NPs were synthesized at 200 degrees C. And the h-ITO NPs can also be synthesized when the temperature was as low as 110 degrees C by an 8-h reaction. The lowest resistivity of 1.258 Omega cm can be reached when the volume ratio of DI water to GL was 1:1, the reaction temperature and time were 200 degrees C and 8 h, respectively. Moreover, the mechanism of the influence of experimental conditions on the resistivity of ITO NPs was also analyzed.