Abstract: In recent years,with the improvement of living standards,the healthy living and safety protection have received a great deal of attention,and the detection of toxic,flammable and explosive gases has been paid increasing concern,especially in the fields such as emission testing,fire control,petrochemical industry and aerospace. Metal oxide semiconducting gas sensors are widely used in the field of gas sensing due to their high sensitivity,low cost,and good stability. As a typical n-type wide bandgap semiconductor,indium trioxide （Indium Oxide） has become a good gas-sensing material due to its transparent conductivity,low resistivity and good gas sensitivity. In this paper,the research progress of micro/nano-structured indium oxide gas sensor in recent years is reviewed. The structure,gas sensing mechanism,different morphology,metal and metal oxide modification and carbon composite of indium oxide gas sensing materials are discussed. The problems and the trends of indium oxide gas sensor are also analyzed.