Sb-doped SnO2 (ATO) thin films have been prepared using the spin coating method by selecting the proper amount of acetylacetone as solution modiifer. All ATO powders and iflms exhibited the cassiterite rutile-like structure in a crystal size below 10 nm under all the experimental conditions and a non-previously reported crystal structure was observed at high acetylacetone loads. The acetylacetone molar ratio inlfuenced notably the optical and electrical properties of ATO iflms. When prepared at an acetylacetone molar ratio of 4, ATO iflms exhibited optical transparencies above 90% in the visible region and above 40% in the UV region for thicknesses of 100 and 300 nm. Films in a thickness of 100 nm and at an annealing temperature of 650℃ accounted for a high transparency of 97% in the visible wavelength. Films prepared at an acetylacetone molar ratio of 4 exhibited an electric resistivity of 1.33×10-3 Ω·cm at an annealing temperature of 650℃. The optimal Sb content for ATO iflms was found to be 8 at%. The relationships among the properties of starting solutions, the experimental parameters, and properties of ATO iflms are discussed.