Abstract: In order to promote the detection accuracy and separation efficiency of CO₂ expanded cut tobacco in blended cut tobacco of cigarette, a separator for separating CO₂ expanded cut tobacco from blended cut tobacco was designed by using CO₂ expanded tobacco as a tracer and combining the chemical specific gravity method with fluid dynamics. The device mainly consists of a separation system, a collection system, a power system, an automatic liquid level control system and an electric control system. Following the introduction of the separating solution, the cut tobacco sample immersed in the solution was stirred and turned into upper, middle and lower layers under the action of floatation, stratification and filtration due to the density difference between expanded tobacco and other components in the cut tobacco sample. The designed separator was tested with the blended cut tobacco of "Septwolves" brand cigarette provided by China Tobacco Fujian Industrial Limited Corporation. The results showed that the separator featured high precision, good accuracy and repeatability. The absolute error was less than 0.25%, the standard deviation ranged from 0.17% to 0.38%, and the coefficient of variation was less than 5%. The separation and detection efficiency increased by more than 80% compared with the manual separation method. This technology supports the promotion of tobacco blending accuracy and uniformity in cigarette production.