Infrared radiation characteristics measurement is the main method for the precaution and discrimination of missiles,relevant research is worthy in military application.And the atmosphere amending is a difficulty which influences precision in infrared radiation characteristic measurement.The method amending atmosphere influence is introduced,which places large area gray body beside the target.After academic analysis and experiment research,it is found that the “black body demarcation curve” and “reference curve” intersect at the atmosphere temperature point,and the slope amending coefficient and offset amending coefficient could be calculated based this two curve.After corresponding amending on target gray,the infrared radiation characteristics could be calculated by rule and line.