Abstract：Saline-alkali soil is one of the most common environmental stressful factors in the agriculture ecosystem, and severe‐ ly limits plant growth and development, thus greatly reducing the use of land with salinization-alkalization. Songnen plain is one of the three typical region representing soda saline-alkali soil in the world, and remains to be developed as potential land re‐ source because of higher contents of Na2CO3 and NaHCO3 in soils. Therefore, improving saline-alkali soil is of great impor‐ tance for enchancing the adaptive cultivation of plants. Furfural residue has lower pH value and contains higher organic matter, and could be largely utilized as soil conditioner because of its lower cost. To explore the effect of furfural residue on regulation of physico-chemical properties and bacterial community diversity of saline-alkali soil, we performed a preliminary experiment by planting Vicia villosa Roth in saline-alkaline soil. In this study, depending on the preliminary experiment, three treatments were designed by the addition of 0, 5% and 10% furfural residue, respectively, and pot experiment was carried out in a green‐ house for 3 months to investigate the changes of soil microbial diversity and physiological metabolites in Vicia villosa Roth. The results showed that application of furfural residue effectively lowered the pH value and salt content in saline-alkali soil, and increased the Sobs and Shannon index in soils. In detail, Proteobacteria, Actinobacteria, Firmicutes, and Chloroflexi be‐ come the dominant bacteria under supply of furfural residue. Compared with the treatment without addition of furfural residue, the treatment with addition of 5% furfural residue obviously reduced the ammounts of the Proteobacteria and Green Curvular‐ ia, but significantly increased the community of other bacterias. However, application of 10% furfural residue significantly in‐ creased the enrichment of Actinomycetes, Bacteroides, Bacillus and Patescibacteria in soils, and lowered the community of the other bacteria. The application of 5% furfural residue not only significantly increased the biomass and root length of Vicia villo‐ sa Roth compared with the control (P<0.05), but also increased the accumulation of chlorophyll, soluble sugar and proline in leaves of Vicia villosa Roth. Meanwhile, the application of 5% furfural residue obviously increased the activities of peroxidase (POD), catalase (CAT) and superoxide dismutase (SOD) in the leaves compared with the treatment without furfural residue (p< 0.05), thus promoting the adaptability of Vicia villosa Roth in saline-alkali soil. Data shows that the application of 5% furfural residue revealed the best effect in improving saline-alkali soil. This study indicates that furfural residue can effectively alleviate the damage of salt-alkali stress to the plant by improving the physico-chemical properties and increasing microbial diversity of saline-alkali soil, and significantly lower the toxicity damage of salt stress ions to the root system, thus improving the growth and development of the root system, and promoting photosynthesis and the accumulation of dry matter. This study provides a better reference for the reasonable applivation of furfural residue in improving cultivation of plants in saline-alkali soil.