Abstract: In order to explore the effects of different carbon-increasing and nitrogen-reducing measures on soil nutrients and microbial community structure of tobacco planting fields, taking flue-cured tobacco Yunyan 116 as the research object, conventional fertilization (CF) and 3 carbon-increasing and nitrogen-reducing treatmentsOn the basis of conventional fertilization, reduce nitrogen by 10% and add mushroom residue organic fertilizer 750 kg/hm² (MO), high carbon base fertilizer 600 kg/hm² (HB), and biological organic fertilizer 750 kg/hm² (BO) were conducted, and the soil carbon and nitrogen nutrients and microbial community structure were determined. The results showed that compared with the conventional fertilization CF, the contents of total carbon and organic matter in the soil treated with MO were significantly increased by 23.62% and 25.05%, respectively; The relative abundance of the two dominant bacterial phyla, Acidobacteria and Chloroflexi, was higher in MO treatment, and the relative abundance of Bradyrhizobium was also significantly higher than that in other treatments. The relative abundance of the above bacterial groups in the HB treatment was just lower than the MO treatment, and the relative abundance of the above bacterial groups in the BO treatment was the lowest. The relative abundance of HB treatment was the lowest among pathogenic bacteria such as Humicola and Fusarium. The results from this study have shown that mushroom residue organic fertilizer combined with nitrogen reduction measures has the best effect in promoting the release of soil carbon and nitrogen nutrients, improving soil microbial community structure, and improving nutrient utilization.