The electro-optical effect of jamming smoke screen depends on the composite of the smoke agent.The paper introduced the influence factors of IR extinction property with the investigations of optical and microphysical characteristics of aerosol.Take NaCl as the filler,and compare the attenuation performance of NaCl water vapor on infrared radiation under different concentration,dosage and target temperature conditions by experiment.Experimental results show that increasing the concentration and dosage of NaCl aerosol is good for enhancing extinction ability of water fog.IR extinction performance was calculated and analyzed according to Mie theory for water vapor whose granularity distributing keeps up logarithm normal distribution.The transmissivities are 38% at 3.5μm and 55% at10.591μm,respectively.At last,the approach to choose interference filler with good electromagnetism and suspending characteristics is put forward.