Gas sensor can monitor the composition and content of trace toxic and harmful gases in environment. As the core of gas sensor technology, the performance of the sensor is closely related to the properties of the gas sensing materials. Recent work focused on development of novel sensitive materials with a large specific surface area, a high carrier mobility, a high catalytic activity, a wide measurement range and a good long-term stability to build high-performance gas sensors. Among them, halide perovskite materials are a potential option for gas-sensitive materials due to their advantages (i.e., high room temperature carrier migration rate, sensitive surface properties, directly adjustable band gap and simple preparation). The toxic and harmful gas detection applications were analyzed and its sensing mechanism was clarified based on the advantages of halide perovskite in gas sensors. It is necessary to summarize the existing halide perovskite gas sensing materials. This review represented halide perovskite sensitive materials, discussed their working mechanisms in gas sensors, and summarized the application of halide perovskite gas sensors in NOx, NH3, H2S and volatile organic compounds (VOCs). Halide perovskite gas sensors can be used for detection NOx gas. Especially, MA- or Cs-based halide perovskite gas sensors with a bipolar charge transfer can achieve a high response/recovery speed at low operating temperatures and quickly and accurately detect NO2 and NO gas. Some recent work indicate that the Cs-based halide perovskite materials have better stabilities rather than the MA-based halide perovskite materials, so the as-prepared Cs-based halide perovskite gas sensors have better repeatability than the MA-based halide perovskite gas sensors. NH3 detection is another important application of halide perovskite gas sensor. This is because NH3 pollution seriously threatens human health and safety, and affects the sustainable development of ecological environment. Also, NH3 is also a metabolite of the human body and widely exists in exhaled gas, which can be used as a marker for a variety of diseases for non-destructive diagnosis in clinical medicine. The perovskite film color changing, resistance changing, and reversible weak bond action are mainly used to achieve ammonia detection. Moreover, the detection of ammonia is also extended from MA- or Cs-based halide perovskite to PEA-based halide perovskite. The material dimensions also extend from three dimensions to two dimensions, and ammonia can be efficiently detected at room temperature. H2S is an important chemical raw material, and a highly toxic and dangerous gas. In recent years, H2S poisoning accidents occur frequently. There is a coincidence in the fact that the halide perovskite sensitive materials with high performance, low cost and small size are an ideal option for H2S gas sensors and H2S gas alarms. The FAPbBr3-based sensor has an extremely high H2S response sensitivity (at room temperature), and works well under both dark and half-light conditions, especially in half-light condition. The assembled gas sensor can be used to detect oxidizing and reducing gases and a variety of VOCs due to the bipolar nature of halide perovskite. VOCs are extremely volatile and accompanied by a pungent odor, and their emission can seriously pollute the environment and threaten human-being health. To meet different needs, A/B bit substitution and halogen or pseudohalogen doping were used to achieve the superior device sensing performance. Summary and prospects As a recent research hotspot, halide perovskite sensitive materials with the advantages (i.e., strong stability, good selectivity and low working temperature) are one of the effective options of gas sensitive materials. Halide perovskite sensitive materials are also developed from the simple original MAPbI3 system to different systems. The corresponding applications of gas sensors were also enriched to detect oxidizing gases, reducing gases, and a variety of VOCs. This review summarized the recent research progress on halide perovskite gas sensors to provide a reference for halide perovskite gas sensors used in related fields. In the future research, we proposed 1) to further explore more perovskite (i.e., double perovskite materials such as MA2AgBiI6, Cs2AgBiI6, Cu2AgBiI6, and perovskite-like materials such as AgBiI4, CuBiI4, etc.) materials, and expand their application in the detection of toxic, harmful gases and VOCs gases; 2) to grow more perovskite single crystal sensitive materials instead of halide perovskite polycrystalline sensitive materials, and develop more perovskite single crystal sensors with superior photoelectric properties and sensing properties; and 3) to use halide perovskite gas sensors with high precision, miniaturization, a low power consumption and low cost in medical detection (i.e., human metabolites, neurotransmitters and various disease-related substances), thus achieving a deep cross-integration of medical and industrial fields.