Acidity and infrared attenuation ability of water,methanol and ammonia using titanium tetrachloride as liquid smoke agent were studied in detail. In small trunk,the smog of water and methanol is acid and the smog of 10%-20% ammonia is almost neutral; infrared attenuation ability of all these smog is satisfactory. In large trunk,the smog formed by 14% ammonia with titanium tetrachloride with proportion of 13：1 to 16：1 is neutral; the target-temperature increases from 50 ℃ to 198 ℃,the 3-5 μm infrared radiation rate of the neutral smog falls from 74% to 20%,the 8-12 μm infrared radiation rate of the neutral smog maintains upon 95%.