Abstract: With the stringent enforcement of environmental regulations, maintaining the safe and stable operation of desulfurization systems has become critical for coal-fired power plants to achieve ultra-low emissions. The large-scale scaling issue observed in the turbulence generator of a desulfurization tower after co-firing biomass (Salix psammophila) at a specific power plant is investigated, and the scaling mechanisms as well as the impact of biomass co-firing on scaling characteristics are analyzed. Field-collected scale samples exhibited an interwoven surface structure with high hardness. Infrared spectroscopy revealed hydroxyl (O—H) and hydrocarbon (C—H) absorption peaks in the scale, indicating the presence of unburned biomass residues on the turbulence generator surface. Industrial analysis further demonstrated that the co-fired biomass had significantly higher ash content and lower volatile matter compared to typical coal and other agricultural biomass, leading to reduced combustion efficiency and increased unburned substances, thereby exacerbating scaling. Elemental analysis identified CaSO₄·2H₂O (gypsum) as the primary component of the scale, confirming gypsum-dominated scaling. Flow field simulations highlighted uneven distribution between the turbulence layer and flue gas inlet, creating localized vortices and low-velocity zones that promoted supersaturated gypsum crystallization and deposition. Chemical kinetic analysis suggested that organic components introduced by biomass co-firing interacted with gypsum crystal growth through cross-linking effects, accelerating scale formation. The root causes of scaling were attributed to two factors: Incomplete biomass combustion introduced unburned organic matter into the desulfurization system, providing heterogeneous nucleation sites; Elevated gypsum supersaturation in the desulfurization slurry combined with flow field defects facilitated preferential crystal deposition. To address these issues, comprehensive optimization strategies are proposed: Enhance biomass pretreatment (e.g., particle size uniformity and drying efficiency) to improve combustion completeness; Optimize combustion parameters (e.g., co-firing ratio, furnace temperature distribution) to minimize unburned particles; Adjust desulfurization operational parameters (e.g., slurry pH, liquid-to-gas ratio) to control gypsum supersaturation; Upgrade dust removal equipment to adapt to fly ash characteristics post co-firing; Install real-time salinity monitoring in the desulfurization tower for crystallization control; Redesign turbulence generator geometry or install flow guides to homogenize flow distribution. These integrated measures will enhance system stability and provide theoretical and engineering guidance for balancing environmental and economic performance in biomass co-firing applications.