Saline-alkali soil degradation poses a severe challenge to agricultural sustainability and food security in arid and semi-arid regions worldwide. This review systematically summarizes the processes, mechanisms, and application prospects of earthworm-biochar coupling for the remediation of saline-alkali soils. Earthworms, functioning as "ecosystem engineers," markedly improve soil physical structure through burrowing, ingestion, and casting, reducing bulk density, increasing porosity and the proportion of water-stable aggregates, and enhancing soil water retention and aeration; meanwhile, their metabolic activities promote organic matter transformation and nutrient cycling, regulate microbial community structure, and enhance key soil enzyme activities such as urease and phosphatase, thereby alleviating salt-alkali stress and promoting plant growth. Biochar's high surface area and abundant pore structure, and surface functional groups, effectively lowers soil sodium adsorption ratio (SAR) and electrical conductivity (EC), and increases cation exchange capacity (CEC) and organic carbon content through physical adsorption, ion exchange, and pH buffering, synergistically enhancing soil fertility and salt leaching efficiency. The combined application of earthworms and biochar can markedly optimize the soil microenvironment and improve crop yield and quality, although high doses of biochar may exert growthinhibitory toxicological effects on earthworms, necessitating rational application rates. This review further envisions the construction of an "earthworm-biochar-microbe" ternary synergistic remediation system and the development of modified nano-biochar, providing systematic theoretical support and technical pathways for the green, efficient, and sustainable management of saline-alkali soils.