To address the low indium recovery rate obtained from secondary zinc oxide weak acid residues, this work focused on the process intensification of conventional acid leaching technology. Key operational parameters, including sulfuric acid concentration, liquid-to-solid ratio, reaction temperature, reaction time, and rotation speed, were systematically investigated to explore their effects on indium leaching efficiency, with the aim of identifying the optimal leaching conditions for practical application. Experimental results demonstrated that under the specific conditions, sulfuric acid concentration of 3 mol/L, liquid-to-solid ratio of 4∶1, reaction temperature of 80℃, reaction time of 120 min, and rotation speed of 500 r/min, the indium leaching efficiency reached 90.51%. To further enhance indium leaching performance and achieve higher leaching efficiency, subsequent intensive optimization was carried out. The results revealed that under the aforementioned optimal leaching conditions, adding sodium sulfite as a reductant significantly increased the indium leaching efficiency to 93.50%, showing obvious intensification advantages for industrial practice. To unravel the intrinsic leaching reaction mechanism, multiple characterization methods including XRD, SEM-EDS, and XPS were adopted to comparatively analyze solid samples before and after leaching. The characterization results indicated that part of indium was isomorphically embedded in the lattice structure of zinc ferrite. During reductive leaching, redox reactions effectively disrupted the crystal structure of zinc ferrite, facilitating the release of indium elements encapsulated within the lattice into the solution in a soluble form. This mechanism significantly enhanced the leaching effect and realized a substantial improvement in indium extraction efficiency. The outcomes of this study can offer a reliable theoretical basis and technical support for the development of new high-efficiency indium recovery processes from indium-containing zinc residues in the metallurgical industry.