Abstract: Based on numerical calculation of computational fluid dynamics/infrared(CFD/IR),the effects of the covering shelter fixed onto the curved mixing duct on the infrared radiation characteristics of the helicopter infrared radiation suppressor were revealed.The results show that: the infrared radiation intensity of the IR suppressor with covering shelter could be reduced more than 90% in the horizontal plane or the bottom of the vertical plane,if compared with that without covering shelter.With the increase of the slot distance between the mixing duct and the covering shelter,the surface temperature of the covering shelter is decreased monotonously.For three slot distances(5,10 mm and 35 mm) in the present study,the infrared radiation suppressing effect seems more advantageous when the slot distance is 10 mm.