Abstract: To efficiently remove lignin-rich tobacco processing byproduct such as tobacco stems and achieve its high-value utilization, a treatment process combining hydrothermal pretreatment (HTP) and a ternary deep eutectic solvent (DES) composed of choline chloride (ChCl), lactic acid (LA), and ethylene glycol (EG) was employed. The effects of single HTP, single DES and the combined HTP-DES process on lignin removal and component separation selectivity were systematically compared. The results showed that: 1) Under the synergistic effect HTP (100 ℃, 1 h) and DES (100 ℃, 4 h), the maximum lignin removal rate reached 76.27%, which was significantly higher than that of the single DES treatment (100 ℃, 4 h; 57.71%), and the cellulose retention rate was more than 90.00%, indicating good component separation selectivity. 2) Hydrothermal pretreatment effectively destroyed the structure of the lignin-carbohydrate complex (LCC), promoting dissolution of lignin in DES. After DES was reused five times, the lignin removal rate remained above 60.00%, demonstrating good recycling stability and economy. 3) The regenerated lignin exhibited a low molecular weight and an intact structure.