This review discusses the sensitivity and influencing factors of conductometric semiconducting metal oxide gas sensors. Metal oxide gas sensors are widely used for gas detection due to their low cost, flexibility, and ability to detect a wide range of gases. Sensitivity, a key parameter, is influenced by factors such as chemical composition, surface modification, microstructure, temperature, and humidity. The sensitivity of these sensors is closely related to surface reactions, which are affected by the chemical components, surface modifications, and microstructure of the sensing layers. The review highlights that composite metal oxides often exhibit better gas response than single-component materials when the catalytic actions of the components complement each other. Noble metal additives, such as platinum, gold, and palladium, can enhance sensor sensitivity through the "spillover effect." Additionally, the microstructure of the metal oxide layers plays a crucial role in determining sensitivity. Smaller grain sizes can increase sensitivity, but excessive reduction may lead to structural instability. Porous structures with high surface areas are beneficial for gas sensing, as they provide more reaction sites and improve the interaction between the sensing material and target gases. The sensing mechanism involves changes in conductivity due to surface reactions between the gas and the metal oxide. The presence of water vapor can decrease sensitivity by altering the surface chemistry and reducing the number of active sites. Temperature also significantly affects sensitivity, with optimal performance typically occurring at specific operating temperatures. Humidity and temperature are critical factors that influence the performance and reliability of metal oxide gas sensors. The review concludes that optimizing the structure, composition, and microstructure of metal oxide materials is essential for developing high-performance gas sensors.This review discusses the sensitivity and influencing factors of conductometric semiconducting metal oxide gas sensors. Metal oxide gas sensors are widely used for gas detection due to their low cost, flexibility, and ability to detect a wide range of gases. Sensitivity, a key parameter, is influenced by factors such as chemical composition, surface modification, microstructure, temperature, and humidity. The sensitivity of these sensors is closely related to surface reactions, which are affected by the chemical components, surface modifications, and microstructure of the sensing layers. The review highlights that composite metal oxides often exhibit better gas response than single-component materials when the catalytic actions of the components complement each other. Noble metal additives, such as platinum, gold, and palladium, can enhance sensor sensitivity through the "spillover effect." Additionally, the microstructure of the metal oxide layers plays a crucial role in determining sensitivity. Smaller grain sizes can increase sensitivity, but excessive reduction may lead to structural instability. Porous structures with high surface areas are beneficial for gas sensing, as they provide more reaction sites and improve the interaction between the sensing material and target gases. The sensing mechanism involves changes in conductivity due to surface reactions between the gas and the metal oxide. The presence of water vapor can decrease sensitivity by altering the surface chemistry and reducing the number of active sites. Temperature also significantly affects sensitivity, with optimal performance typically occurring at specific operating temperatures. Humidity and temperature are critical factors that influence the performance and reliability of metal oxide gas sensors. The review concludes that optimizing the structure, composition, and microstructure of metal oxide materials is essential for developing high-performance gas sensors.