As a special form of pollution emissions,the fumigation gas of CH 3-Br discharged by log in train causes serious damage to the nervous system and respiratory system of human and animals.This paper took Tongjiang log fumigation site for example,selected body source model of AERMOD to simulate the diffusion of fumigation pollution and analyzed the impact of pollution.Results showed that high concentration of CH3-Br was centered in the surroundings of fumigation lines and most occurred at night.The farther away from the fu-migation line,the lower the excess standard rate of CH 3-Br.With the prediction and the calculated maxi-mum distance,pollution control measures were proposed for the fumigation field.