Abstract: The speed of weighing belt in CO₂ pregnated cut tobacco feeding system was unvaried despite of the fluctuation of tobacco flow, it resulted in instable tobacco expansion.The CO₂ pregnated tobacco flow was calculated by analyzing the weight change of the tobacco in vibrated storage bin, the speed of metering belt MC-45 was automatically controlled to stabilize the tobacco flow feeding into the expansion tower, the uniformity of moisture content in expanded tobacco was thus increased and the amount of unsatisfied expanded tobacco was decreased accordingly.