In AF2/KDF2 filter rod maker, triacetin is applied to tow by means of the centrifugal force generated by an applicator roller rotating at a high speed. Poor atomization may result in fused holes in filter rod, and uneven application may result in hardness fluctuation of filter rods. The hardware and control unit were improved by taking the atomizing and spraying system in KDF3 and KDF4 filter rod makers as a reference. Triacetin was well atomized and evenly sprayed on tow through nozzles at constant pressure. The test results showed that the process capability index for filter rod hardness raised from 0.6 to 1.13, the rate of defective filter rod decreased from 0.54% to 0.35% and the average consumption of triacetin reduced from 0.0949 to 0.0933 kg per thousand filter rods. The consistence of filter rod quality was improved.