This paper systematically reviews the research advancements in indium oxide (In2O3 )-based gas-sensitive materials and focuses on their potential applications in environmental monitoring and safety. It provides an in-depth analysis of the structure, properties and gas sensing mechanisms of indium oxide, detailing the impact of various synthesis methods (such as hydrothermal and chemical vapor deposition) on the microstructure and performance of the materials. Additionally, this paper discusses the applications of modification techniques, including element doping, material loading and semiconductor compositing in enhancing gas sensitivity. It also analyzes current research challenges and future directions, offering significant perspectives and directions for further research and application of indium oxide-based gas-sensitive materials.