To　further　develop　sensing　materials　for　NO2　gas　detection　practical　application,　the　operating　temperature　of　the　sensor　should　be　significantly　reduced.　In　this　paper,　In2O3　flowers　were　prepared　by　the　microwave-assisted　hydrothermal　method.　Then,　In2O3　was　doped　using　TAA　(thioacetamide).　The　prepared　S-doped　In2O3　flowers　have　good　gas　sensitivity　and　significantly　reduced　operating　temperature.　When　exposed　to　10　ppm　NO2　gas,　the　corresponding　response　was　250　at　118　degrees　C.　It　can　be　demonstrated　by　the　first　principle　calculations,　in　which　the　doping　of　S　atoms　changes　the　electron　structure　of　In2O3　from　semiconductor　to　metal　with　a　lower　potential　barrier.　Then,　significantly　affects　the　electron　crossing　the　intergranular　potential　barriers.　Therefore,　the　operating　temperature　of　the　sensor　can　be　reduced.　Our　research　results　will　provide　new　research　ideas　and　technical　approaches　for　designing,　fabricating,　and　applying　a　new　generation　of　In2O3　gas　sensors.