Transition metal oxide nanowires have attracted considerable attention due to their physical characteristics, chemical characteristics, and versatile applications. Among them, indium oxide (In203) nanowires demonstrate promising structure and electrical properties. Simultaneously, it used to be the reactants to synthesize indium zinc oxide (IZO) by solid-state reaction. The applicability would be highly related to the microstructure and synthesis process. Hence, study of conversion kinetics of IZO is essential. However, only few studies have mentioned the formation process of IZO and the solid-state diffusion mechanism. In this work, we successfully observed the transformation of novel IZO nanowire from interesting diffusion behavior between single-crystalline In2O3 nanowires and zinc oxide (ZnO). High resolution transmission electron microscope (HRTEM), fast Fourier transform (FFT) diffraction patterns and energy-dispersive spectrometer (EDS) were used for structural and compositional analysis. Based on the HRTEM images and the corresponding FFTs, the triclinic IZO was defined. Meanwhile, the in-situ TEM and EDS analysis provide the formation behavior and elemental distribution to elucidate the diffusion mechanism. This work exhibited the IZO nanowires with a unique structure and interesting formation behavior. Moreover, the study provides the improvement of controllability of conversion microstructure for further device applications.