When detecting flame targets formed by combustion，the imaging effects vary significantly in different infrared bands due to their different radiation characteristics. The infrared radiation characteristics in the near infrared（0.9~1.7 μm）， mid-infrared（3.8~4.7 μm），and far-infrared（7.5~13 μm）wavelength bands are analyzed by combining simulation and experiment using a gun flame as the research object. From the gas radiation theory，the infrared radiation characteristics of the spray flame in three bands of 0.9~1.7 μm，3.8~4.7 μm，and 7.5~13 μm are calculated and compared according to the radiative transfer equation. Through radiation imaging experiments，the radiation image information of the response band is collected and compared with the simulation calculation results. The results show that about 10 000 target pixels of mid-wave infrared imaging of the flame at 640×512 resolution contain the most amount of information and its infrared radiation intensity is the largest，about 7 000 effective target pixels of long-wave infrared，but its infrared radiation distribution is the widest and least affected by the environment，and about 3 400 pixels of near-infrared imaging. It provides a basis for the detection and identification of various types of power targets as well as image fusion and information enhancement.