Abstract: The coprecipitation method enables the atomic-level homogeneous mixing of metal ions, effectively mitigating powder composition segregation and enhancing doping uniformity. The non-doped indium zinc oxide (IZO) nanopowders were synthesized by coprecipitation with In:Zn atomic ratio of 1:1 in this study, the effects of final precipitation pH and calcination temperature on phase composition and morphology were investigated, and the optimal process parameters were established. Subsequently, the rare-earth-doped PrIZO, NdIZO, and TbIZO nanopowders were prepared with rare earth (Pr, Nd, Tb):In:Zn atomic ratio of 0.01:1.00:1.00. Thermogravimetric-differential scanning calorimeter (TG-DSC) was adopted to analyze the thermal decomposition, phase transformation, and crystallization behavior of the precursors. Phase structure and composition of both precursors and calcined powders were characterized by X-ray diffraction (XRD). The scanning electron microscope (SEM) and transmission electron microscope (TEM) were utilized to examine the micro-morphology and particle size distribution, while the elemental composition and distribution were verified by energy disperse spectroscopy (EDS) and Fourier transform infrared spectroscopy (FT-IR). The results demonstrate that, the rare earth doping effectively modulates the thermal behavior, crystallization, and microstructure of IZO powders. Uniform, the well-dispersed and high-sphericity doped IZO nanopowders are successfully fabricated, and the influencing mechanism of rare earth elements on the structural and microscopic properties of IZO precursors and calcined powders is clarified.