The effects of different infrared radiation (IR) temperatures (100， 110， 120 ℃) and radiation time (2.5， 5， 10 min) on the microbial population and quality of carrot powder with high bacterial load were firstly investigated， the effects of infrared radiation-freezing and infrared radiation-tempering treatment on the microbial population， color and carotenoid quality of carrot powder were further investigated according to the principle of the fence effect. Infrared radiation treatment at 100 ℃ and 10 min reduced bacteria， mold and yeast by 1.9 lg(CFU/g) and 2.32 lg(CFU/g)， respectively. Infrared radiation at 110 ℃ and 5 min reduced bacteria and fungi by 1.58 lg(CFU/g) and 2.57 lg(CFU/g)， respectively. The water activity of carrot powder decreased from 0.238 to 0.123 and 0.147， respectively. The total carotenoid content in carrot powder decreased from 308.8 μg/g to 227.8 μg/g and 238.8 μg/g， respectively. The total color difference (ΔE) was determined to be 9.11 and 7.89， respectively. Compared to IR treatment alone， combination of infrared radiation and tempering treatment on the effects of microorganism inactivation in carrot powder was weak， the total content of bacteria remained at 5.40-5.80 lg(CFU/g) after treatment. Mold and yeast counts were significantly reduced through treatment but was not lower than 4.5 lg(CFU/g). While， combination of infrared radiation (100 ℃ and 10 min) and freezing treatment (7 d) finally reduced the bacterial population of 0.25 lg(CFU/g)， while reduced the amount of mold and yeast of 0.28 lg (CFU/g). Under the condition of infrared radiation (110 ℃ and 5 min) and freezing treatment (7 d)， the contents of bacteria， mold and yeast were reduced 0.26 lg(CFU/g) and 0.40 lg(CFU/g). In these conditions， the color， water activity， and carotenoid content of carrot powder were not affected significantly. This experiment provides a reference for the study of infrared radiation combined sterilization of low moisture powder foods.