Abstract: Calcination atmosphere has an important influence on the activity of catalyst. To optimize the preparation process of citric acid sol-gel iron oxide( Fe_2O_3/LA) low-temperature denitrification catalyst and clarify the effects of calcination atmosphere on the low-temperature denitrification performance of Fe_2O_3/LA catalyst,the Fe_2O_3/LA-Air and Fe_2O_3/LA-Ar catalysts were prepared by a citric acid( LA) sol-gel method and the catalysts were characterized by N_2 adsorption desorption( BET),X-ray powder diffraction( XRD),H_2 reduction by heating( H_2-TPR),NH_3-temperature desorption( NH_3-TPD) and X-ray photoelectron spectroscopy( XPS). The results show that Fe_2O_3/LA-Air catalyst has poorer denitrification activity at high temperature compared with Fe_2O_3/LA-Ar catalyst,while it has better denitrification performance at low temperature,especially at 120-240 oC,of which the NOxconversions can reach 80-100%. And its nitrogen adsorption-desorption curve is H_3 type hysteresis loop Ⅱ type isotherm with larger pores. The Fe_2O_3/LA-Air catalyst has a typical H_2 reduction peak of medium and low temperatures at 270 oC,which has strong reduction capacity. The main active ingredients of the catalysts calcined at two atmospheres are γ-Fe_2O_3. The contents of Fe~(3+) and surface adsorption oxygen Oβin Fe_2O_3/LA-Air catalyst are 3.24% and 48.24% higher than those of the Fe_2O_3/LA-Ar,repectively. For the Fe_2O_3/LA-Ar catalyst,its peaks of ammonia desorption at moderate and high temperatures all move towards high temperature,and the peak area of ammonia desorption at high temperature is larger than that of Fe_2O_3/LA-Air catalyst,so there are more Lewis acid sites. However,the Bronsted acid sites of Fe_2O_3/LA-Air catalyst are more than those of Fe_2O_3/LA-Ar catalyst. These factors are responsible for that the denitrification activity of Fe_2O_3/LA catalyst calcined in air atmosphere at low temperature is better than that of Fe_2O_3/LA catalyst calcined in argon atmosphere.