Abstract: In order to investigate the effects of conservation tillage on nutrient content, bacterial community structure and diversity in black calcareous soil farmland, based on soil chemical analysis and Illumina high-throughput sequencing technology, differences in soil nutrient indicators and bacterial community composition between conservation and traditional tillage modes were compared. The results showed that compared to the traditional mode, the alkaline nitrogen, available phosphorus, available potassium, and organic matter content under the protective tillage mode were significantly increased by 17.75%, 10.98%, 7.62% and 12.89%. The diversity and evenness of bacterial communities significantly improved. The conservation tillage model optimized the bacterial community structure, enriched Proteobacteria, Acidobacteria, Gemmatimonadetes, Bacteroidetes, Nitrospirae, Rokubacteria, and Planctomycotes that promotes nitrogen transformation, improve crop drought resistance, and stress resistance. And enriched Bradyrhizobium, Rhodanobacteria, KD4-96, Rubrobacter and Mesorhizobium which played important roles in plant nitrogen fixation and nutrient transformation. These dominant groups were significantly positively correlated with environmental factors and maize yield, thereby improving soil fertility and promoting yield increase.