Abstract: Manganese oxide (MNO_x) based catalysts has an excellent performance in the removal of nitrogen oxides (NO_x) by selective catalytic reduction with ammonia (NH₃-SCR) at low temperature. However, at present, there was a lack of effective understanding of the key factors controlling the low-temperature activity of the catalyst at the molecular and atomic level. Thus, it was difficult to adopt a controllable strategy to achieve efficient catalytic conversion of NO_x at a wider temperature window and a lower temperature. Based on the latest research progress, this paper reviewed the influence of factors such as catalyst preparation method, catalyst carrier, hetero-heteroatom doping, and catalyst morphology on the denitration performance of MNO_x-based catalyst NH₃-SCR, and then deeply revealed the mechanism of denitration of MNO_x-based catalyst as well as briefly introduced the catalysts sulfur and water resistance mechanism. In addition, the future development of low-temperature NH₃-SCR denitration reaction of MNO_x-based catalysts was prospected.