Abstract: By incorporation of a special cigarette smoke generator and air circuit switching and dilution techniques,a device for real-time determination of the aerosol concentration in mainstream cigarette smoke puff by puff was set up,and the samples of 5 cigarette brands were tested.The results showed that the device worked stably,the average number of the aerosols of the 5 samples ranged from 1.39×10⁹ to 3.71×10⁹ per cm3 with the variation coefficient below 9%.