Abstract: To achieve the resource utilization of industrial solid waste and promote green and low-carbon development, an innovative strategy was developed to prepare solid waste-based concrete through co-utilizing desulfurization ash and beneficiation tailings. The effects of desulfurization ash content on the workability, mechanical properties, durability, environmental safety, and hydration mechanism of the concrete were systematically investigated. The results showed that, through mix proportion optimization, the optimal desulfurization ash content was determined to be 25% (TW25), corresponding to a binder composition of 6% cement, 34.5% blast furnace slag, 34.5% steel slag, and 25% desulfurization ash. At this ratio, the concrete slurry exhibited good workability, with initial and final setting time of 185 minutes and 374 minutes, respectively, and demonstrated favorable spread and slump characteristics. Compressive strength tests revealed that TW25 achieved a 28-day compressive strength of 40.53 MPa, exceeding the C30 concrete standard specified in the Code for Design of Concrete Structures (GB/T 50010-2010). In terms of chloride ion resistance, TW25 exhibited electric fluxes of 561 C at 3 days and 124 C at 28 days, indicating excellent resistance to chloride ion penetration. Leaching tests for heavy metals and \mathrmSO_4^2- showed that the concentrations of hazardous substances in all specimens were below the limits specified in the Standards for Drinking Water Quality (GB 5749-2022), indicating high environmental safety. Hydration product analysis revealed that the incorporation of desulfurization ash led to the formation of gypsum (CaSO₄·2H₂O) and ettringite in the concrete, which was closely related to the \mathrmSO_4^2- and calcium sources provided by the desulfurization ash. In particular, TW25 exhibited a synergistic effect among desulfurization ash, steel slag, and blast furnace slag, which promoted the formation of ettringite (approximately 1 μm in length) and calcium silicate hydrate gel (C—S—H). The increase in the binding energies of Si 2p, Ca 2p, Al 2p, and O 1s orbitals in the hydration products of TW25 confirmed the enhanced crystallization and polymerization of Ca-, Al-, and S-containing hydration phases. The formation of multiple hydration products improved the microstructure and significantly enhanced the mechanical properties of TW25. This study provides a theoretical foundation for the high-value utilization of industrial solid waste and the development of low-carbon concrete.