Abstract: Much has been done on absorption of sound in water fog.The goal of this paper is to apply the phenomena "absorption of sound in water fog" to duct sound elimination system.In the experimental setup,the water fog is produced by 5 ultrasonic transducers.The fog quantity is controlled by altering the voltage.The method used in this experiment is to measure the transfer loss.The experimental results indicate that the water fog can effectively absorb sound above 200Hz.The higher the frequency,the stronger the absorption is.Based on the good experimental results and the controllability for the degree of water fog,the proposed method is useful in extending the field of active noise control in duct system.