Abstract: In order to improve the quality of tobacco stems, an online pilot test of ultrasonic stem washing based on traditional stem washing technology was conducted to investigate the effects of different ultrasonic washing frequencies on the physical properties and chemical components of tobacco stems, and to analyze the mechanism of ultrasonic washing on the sensory quality of cut stems. The results showed that: 1) The sensory quality of cigarette samples containing cut stems washed by 40 kHz ultrasonic wave were better. 2) At the same temperature and washing time, compared with traditional washing, the moisture content in tobacco stems after 28 kHz and 40 kHz ultrasonic washing was not different, the cleanliness was significantly improved, the overall color difference was smaller, and the microstructure of the ducts was deformed. Compared with 28 kHz ultrasonic washing, the filling value of tobacco stem was better after 40 kHz washing. 3) The variations of nicotine, total sugar and reducing sugar mass fractions, sugar/nicotine ratio and nitrogen/nicotine ratio in tobacco stems contributed to the difference in sensory quality of cut stems in cigarettes. Therefore, 40 kHz ultrasonic washing could be used to improve the cleanliness and chemical composition of tobacco stems, maintaining their filling value, and effectively promoting their sensory quality.