Abstract: To reduce the fluctuations of tobacco flow and moisture content in cut tobacco after CO₂ sublimation caused by the manual regulation of the frequency converter in the metering belt, the control system was modified based on PLC technology. Taking the travel distance from tobacco inlet to outlet of the metering belt as a control cycle, the weight of tobacco on the belt was determined by the difference of tobacco weight in the vibrating hoper in a control cycle; the throughput of dry ice impregnated tobacco was automatically controlled via empirically setting the throughput value, calculating the operating frequency of the belt within a control cycle and modifying the frequency control program. The expanded tobacco for cigarette brand A was tested in Guangzhou Cigarette Factory, the results showed that the incidence and duration that tobacco throughput exceeded the standard value after CO₂ sublimation decreased by about 0.56 times/h and 175.04 s/h respectively, the range and standard deviation of moisture content in tobacco reduced by 0.27 and 0.027 percentage points respectively. The consistency of tobacco throughput and moisture content in tobacco was effectively promoted. This technology provides a support for improving the intrinsic quality of expanded tobacco.