In this paper, the indium tin oxide (ITO) thin ﬁlms were prepared by a sol-gel spin coating method and then annealed under different temperatures (400, 500 and 550°C) in a mixture atmosphere of 3.75% H2 with 96.25% N2 gases. The microstructure, optical and electrical properties of the prepared films were investigated and discussed. The XRD patterns of the ITO thin films indicated the main peak of the (222) plane and showed a high degree of crystallinity with an increase of the annealing temperature. In addition, due to the pores existing in the prepared films, the optical and electrical properties of the prepared films are degraded through the sol-gel process. Thus, the best transmittance of 70.0 %in the visible wavelength region and the lowest resistivity of about 1.1×10-2 Ω-cm were obtained when the prepared film was annealed at 550°C.