In order to explore the effects of different organic fertilizers on nitrogen mineralization, soil enzyme activities and soil microbial communities in tobacco-planting soil, a lab culture experiment was conducted with different organic fertilizers (plant-source organic fertilizer, sesame cake fertilizer, biochar organic fertilizer) under the condition of equal nitrogen (100 mg/kg) input and 30 ℃, the changes of nitrate nitrogen and ammonium nitrogen contents, soil enzyme activities and bacterial community diversities were analyzed in different culture periods. The results show that different organic fertilizers increase soil mineral nitrogen content, nitrogen mineralization amount and rate are the highest under cake fertilizer in the early culture stage, while the highest under biochar organic fertilizer in the later culture stage. Biochar and plant-source organic fertilizers significantly improve the activities of soil urease and nitrate reductase, while sesame cake fertilizer significantly improves the activities of protease and sucrase. Compared with no organic fertilizer treatment (CK), organic fertilizers significantly increase soil bacterial diversity, the dominant bacteria phyla are Proteobacteria, Acidobacteria, Bacteroidetes and Planctomycetes, and the dominant bacteria genera are Sphingomonas and RB41. Sphingomonas is the highest under CK, while RB41 is the highest under biocarbon organic fertilizer. Sphingomonas is positively correlated with sucrase activity, but negatively correlated with urease and nitrate reductase activities. Bacterial community structure under biochar organic fertilizer is significantly different from those of other treatments. In conclusion, sesame cake fertilizer and biochar organic fertilizer are beneficial to promote nitrogen mineralization in early and late stages and increase the amount of nitrogen mineralization, respectively, and the latter also has the highest the diversity and richness of soil bacteria.