The research on the Infrared(IR)radiation characteristics and vulnerability assessment of aircraft is important for aircraft survivability enhancement.It is also an important aspect of stealth technology.IR radiation from aircraft is used to detect,track,and lock the target.Based on the infrared radiation theory,IR radiation calculation models for three major IR radiation sources including aircraft skin,engine hot parts and plume are built.Based on the models,it is analyzed the factors that affect the IR radiation characteristics of the aircraft,including the fight speed,the engine hot part and so on.At last the relation between IR radiant intensity and target vulnerability is discussed.