The invention discloses a brevibacterium halotolerans with relatively high azotase activity and application thereof in ecological restoration. The brevibacterium halotolerans GDSD21 is collected in the China General Microbiological Culture Collection Center with the collection number of CGMCC No.12402. Nitrogen-fixing bacteria are separated from rhizosphere soils of field-crop roots, further strains with relatively high azotase activity are screened, and finally the efficient nitrogen-fixing bacterium brevibacterium halotolerans GDSD21 is screened. The azotase activity of the brevibacterium halotolerans GDSD21 is obviously higher than that of common production strain azotobacter chroococcum ACCC11103 for microbial fertilizers, and the brevibacterium halotolerans GDSD21 has extensive application prospects in soil improvement, increasing of the soil fertility, ecological restoration of a virgin land, and production of industrialized seedling-rearing inoculation agents, nitrogen-fixing microbial agents and bio-organic fertilizers for vegetables.