Selective catalytic reduction (SCR) of nitrogen oxides (NOx) using ammonia (NH3) is currently the main technology for flue gas denitration. However, the currently widely used commercial catalysts (such as V2O5-WO3 / TiO2, V2O5-MoO3 / TiO2, etc.) have the disadvantages of high operating temperature, narrow active temperature window, and high catalytic cost. Therefore, in recent years, researchers have devoted themselves to the development of low-cost and efficient low-temperature SCR catalytic materials. This paper summarizes the research progress of low-temperature (less than 250 °C) selective catalytic reduction of NOx by unsupported metal oxide catalysts, supported metal oxide catalysts, precious metals, and molecular sieve catalysts. Among them, manganese-based catalysts show good low-temperature selectivity and stability, and have good application prospects. Finally, the research directions of manganese low temperature SCR catalysts are prospected and theoretically designed based on the existing problems.