Abstract: Taking acidified soil as the research object and ‘Langting’ tomato as the crop.The effects of different amounts of lime nitrogen(0,0.5,1.0 g·kg^-1 soil and 1.5 g·kg^-1 soil) on soil acidity, soil microbial community characteristics and tomato yield were studied by pot experiment, in order to clarify the regulation effect of lime nitrogen on facility acidified soil.The results showed that the application of lime nitrogen could significantly increase soil pH,reduce the total amount of soil exchangeable acid, soil exchangeable H⁺ content and soil exchangeable aluminum content.At 60 days after planting, the pH value of the soil treated with lime nitrogen increased by 0.39-1.24 units, the total amount of soil exchangeable acid decreased by 20.39%-40.69%,the content of exchangeable aluminum decreased by 17.05%-44.06%,and the number of soil microbial characteristics increased by 7.84%-10.75%.At the phylum level, the relative abundance of Gemmatimonadetes and Chloroflexi in soil at different stages was increased, and the relative abundance of Proteobacteria was decreased.The relative abundance of Gemmatimonadetes and Sphingomonas was significantly increased at the genus level.The yield of tomato increased first and then decreased with the increase of lime nitrogen dosage.When the dosage was 1.0 g·kg^-1 soil, the yield of tomato was the highest, increasing by 17.97%.Under the conditions of this experiment, the effect was better when the amount of lime nitrogen was 1.0 g·kg^-1 soil.