Abstract: In order to promote the qualified rate of cigarette weight, the weight control system in GD121A cigarette maker was modified. While keeping the density of cut tobacco stream unchanged, an adjustable pressing block device was designed and installed above the suction bands in the trimming areas of front and rear ecreteur discs. Via adjusting the position of suction bands, the pressing blocks assist the ecreteur discs to change the amount of trimmed tobacco and control cigarette weight. The GD121A cigarette maker before and after modification was tested on slim cigarettes of brand "Nanjing (Jinlingshierchai Virginia-type)" in Nanjing Cigarette Factory. The results showed that the qualified rate of average cigarette weight increased from 76% to 97%, which met the technical requirements of cigarette production. The modification did not affect the running status of equipment and the other technical indexes significantly. The overall qualified rate of cigarette weight for 7 GD121A cigarette makers raised by 18 percentage points, it saved 5.18 tons of cut tobacco per month. This technology provides a support for improving the quality of cigarette products and reducing the consumption of tobacco and other materials.