Abstract: Water-washing pretreatment is of great significance for biomass combustion utilization. The distilled spirit lees were separated and pretreated by different washing water under different solid-containing rates. With the proximate, ultimate and TG-MS analyses, the effects of water-washing on the fuel properties of distilled spirit lees were investigated. The results show that water washing has a significant effect on the physicochemical properties of distilled spirit lees. With the decrease of solid-containing rate, the ash content decreases and the volatile content increases. While the fixed carbon reaches the peak when solid-containing rate is 8%. After water-washing, the C content is enriched, and the O content decreases when the solid-containing rate is higher than 8%. Meanwhile, the contents of N and S decrease. The high heat value slightly increases. Therefore, the fuel properties of distilled spirit lees can be improved. With water-washing, the release of permanent gases (H₂O, CO₂, NH₃, NO) decreases during combustion. When the solid-containing rate is 5%, the emission of NH₃ is reduced by 56.6%, and NO reduced by 33.1%. In addition, the water-washing can effectively alleviate the slagging tendency during the combustion of distilled spirit lees. The feasibility of water-washing for distilled spirit lees can be proved. This study can provide a new idea for the efficient and clean disposal of biomass.