【Objective】This study aimed to isolate and identify autotrophic nitrogen-fixing bacteria in vegetation concrete under freeze-thaw conditions and investigate their effects on the physical and chemical properties of vegetation concrete and the growth of ryegrass. 【Method】Autotrophic nitrogen-fixing bacteria GDJ-1 and GDJ-2 were isolated from vegetation concrete that had experienced multiple freeze-thaw cycles by selective nitrogen fixation medium. The strains were identified by morphological, physiological, and biochemical characteristics, 16S rDNA, and phylogenetic analysis. The effects of target strains on physicochemical indexes of vegetation concrete and the growth of ryegrass were explored. 【Result】Strain GDJ-1 was identified as Microbacterium proteolyticum, a Gram-positive bacterium with a round yellow colony. The strain GDJ-1 did not produce oxidase but was capable of producing catalase and it could not degrade gelatin or hydrolyze starch. This bacterium exhibited favorable growth under pH levels that ranged from 7 to 9 and in the presence of sodium chloride (NaCl) concentrations between 0.5% and 2%. After treatment with GDJ-1, the aboveground fresh weight, aboveground dry weight, belowground fresh weight, and belowground dry weight of ryegrass increased by 29.09%, 5.05%, 13.40%, and 16.40%, respectively, compared with the control group. The contents of organic matter, total nitrogen, alkali-hydrolyzed nitrogen, and available phosphorus in vegetation concrete were increased, and the increase of alkali-hydrolyzed nitrogen was 62.95%. Furthermore, strain GDJ-2 was Ralstonia pickettii, a Gram-negative bacterium with a round beige colony. The strain GDJ-2 produced oxidase but did not produce catalase, and was capable of hydrolyzing gelatin and starch. It exhibited favorable growth under conditions with a pH range of 7 to 9 and a sodium chloride (NaCl) concentration of 0.5% to 2%. After treatment with GDJ-2, the aboveground fresh weight, aboveground dry weight, belowground fresh weight, and belowground dry weight increased by 35.71%, 4.93%, 46.38%, and 13.79%, respectively, compared with the control group. The contents of organic matter, total nitrogen, alkali-hydrolyzed nitrogen, and available phosphorus in vegetation concrete were increased, and the increase of available phosphorus reached 35.73%.【Conclusion】There were great differences in morphology and enzyme metabolism between the two strains, but both were capable of enhancing the nutrient condition of vegetation concrete and promoting the growth of ryegrass. In the ecological restoration of vegetation concrete, autotrophic nitrogen-fixing bacteria GDJ-1 and GDJ-2 displayed application potential. GDJ-1 possessed a robust nitrogen fixation ability, effectively converting nutrients in the soil, which was more suitable for regions where the soil was poor or lacking nutrients. However, GDJ-2 demonstrated superior environmental adaptability, especially exhibiting heightened tolerance to alkaline environments, making it more fitting for regions with stringent conditions such as saline-alkaline soils. Considering the necessity for nutrient balance in actual engineering projects, further research can be conducted on freeze-thaw tolerant indigenous phosphate-solubilizing, potassium-releasing, and cellulose-decomposing bacteria, to develop a composite bio-agent tailored for vegetation concrete ecological restoration in freeze-thaw areas.