Abstract: Saline-alkali land, as a significant reserve of arable land resources, is of strategic importance for ensuring global food security and addressing arable land shortages through its ecological restoration and efficient utilization. In recent years, microbial amendment technologies, due to their combined eco-friendliness and sustainability, have received considerable attention and have become a research hotspot in the field of soil remediation. Microorganisms significantly improve the physicochemical properties of saline-alkali soil and promote crop growth through multiple mechanisms, including regulating the soil microenvironment, alleviating salt stress damage to plants, and enhancing soil nutrient utilisation efficiency, thus providing a new pathway for saline-alkali land management. This article reviews the current research progress on the improvement of saline-alkali soil by applied microbiology, including the diversity of microbial germplasm resources for improving saline-alkali soil, the mechanism of action and application effect of strains, and the improvement of excellent strains. Existing research indicates that there is a wealth of microbial germplasm resources available for the improvement of saline-alkali soils, encompassing Bacillus, Pseudomonas, Streptomyces, Enterobacter, Trichoderma and Arbuscular Mycorrhizal Fungi. Microorganisms improve the soil microecological environment through diverse mechanisms, regulate soil physicochemical properties, inhibit the occurrence of plant diseases, and enhance crop yield and fruit quality. Some microorganisms can neutralise alkaline substances in the soil by producing organic acids through metabolism, regulating soil pH and optimising the plant rhizosphere microenvironment. They can also secrete plant growth hormones, degrade ethylene precursor substances, etc., to promote plant growth and development, synthesise extracellular polysaccharides, functional proteins and other secondary metabolites to improve soil aggregate structure and physicochemical properties, regulate the structural composition and diversity of soil microbial communities, and simultaneously secrete antibacterial active substances to inhibit the reproduction of plant pathogenic microorganisms, prevent and control soil-borne diseases, and improve plant stress resistance by regulating plant immune response reactions. Current research often focuses on single strains, and their field application is affected by the complex environment of saline-alkali land, resulting in limited effects and insufficient stability. Furthermore, the technical system for bacterial agent preparation, storage and standardised application has not yet been perfected, and the interaction and regulation mechanism among microorganisms, plants and soil has not been fully clarified. In the future, focusing on the biological improvement needs of saline-alkali land, multi-omics technology and genetic engineering methods can be combined to analyse the molecular mechanism of microbial action, optimise efficient strain cultivation technology, and simultaneously develop multifunctional compound bacterial agent preparation and supporting application technologies, improve the industrialisation process system, and provide theoretical support and technical guarantee for efficient biological improvement and sustainable utilisation of saline-alkali land from multiple dimensions.