Abstract: In order to reduce the time needed for cigarette length adjusting and the number of dust-sandwiched cigarettes, the cigarette length adjusting device in YJ212 filter assembler was modified. A spring positioning device and a pinion type adjustment screw were designed for ensuring that the adjustment maintained backlash free. The main shaft was modified by checking method to promote the stability of the device. Scales were marked on the compression plate to quantify the adjustment. An air-jet was added to reduce the number of dust-sandwiched cigarettes. The cigarette length adjusting device was tested on cigarette brand "Mount Tai (Red General)" in Jinan Cigarette Factory, the results showed that the frequency of cigarette length deviation decreased by 84.6%, the time needed for cigarette length adjusting shortened by 66.7%, and the percentage of dust-sandwiched cigarettes reduced by 67.5%. This technology provides a support for improving the efficiency of filter cigarette makers.