The invention provides an iron-based low-temperature SCR denitration catalyst and a preparation method thereof. Iron and cerium compounds are taken as active components, or iron, manganese and cerium compounds are taken as active components, titanium oxide is taken as a carrier, the molar ratio of iron, manganese and cerium is 1:(0.5-4):(0.5-1.5), and the molar ratio of iron and titanium oxide is 0.15-0.25. The preparation method comprises the steps of dissolving iron nitrate, manganese nitrate and cerium nitrate in deionized water, adding the titanium oxide, stirring intensely so as to mix the above compounds thoroughly, then performing ultrasonic mixing, putting the mixture into an oven for drying, calcining in an air atmosphere, and then grinding the mixture into powder. The iron-based low-temperature SCR denitration catalyst provided by the invention has an obvious advantage in cost, and meanwhile, the iron-based low-temperature SCR denitration catalyst has higher denitration efficiency under a medium and low temperature.