Abstract：To observe the law of indoor fine particles' thermophoresis, the incense smoke was used as the fine particles source in an environmental laboratory with an artificial hot and cold vertical wall zone, and the scanning electrical mobility sizer was used to measure the decay coefficient of fine particles number concentration near the cold wall under different temperature difference for the indirect comparision of its thermopheresis.Experimental results show that the decay coefficient of fine particles near the surface of cold wall decreases in turn under the temperature difference between the hot and cold surface of vertical wall at 50, 70, 90 ℃. That is, the greater the temperature difference near the vertical wall, the stronger the thermophoresis effect of incense smoke particles tends to be closed to the cold surface, and the larger size of fine particles with thermophoresis effect. When the temperature difference between the hot and cold surface of vertical wall are 70, 90 ℃, it results in obvious thermophoresis effect of fine particles in the range from90 to 170 nm and from 210 to 450 nm respectively.

Keywords：fine particles; effect of thermophoresis; vertical wall