Abstract: To achieve the online precise detection of the recycled tobacco rate in a cigarette maker, this study established a density distribution model of the tobacco rod within the suction groove and developed a corresponding online monitoring system based on industrial PCs. The system performs real-time measurement of the recycled tobacco rate through the integration of four core modules: height detection, data acquisition, data processing, and data service. The results show that: 1) the density distribution of the tobacco rod in the suction groove along the height direction follows an exponential decay law; 2) experimental verification indicates that the average relative error of the recycled tobacco rate calculation model established in this study is 0.93%, indicating high accuracy and fully meeting the requirements of online detection; 3) this system provides reliable data support for the optimization of cigarette production processes, and plays a vital role in stabilizing equipment operation and improving the physical quality of cigarettes.