[Objective] Greater Khingan forest is one of the largest forest areas in China. There are many studies on plant diversity along forest succession in this area, but few studies on microbes. This research studied the impact of forest succession on soil microorganism diversity in Greater Khingan Mountains, which could provide a more comprehensive understanding of the impact of the natural forest protection project on biodiversity. [Methods] Effects of forest succession on soil bacterial diversity were analyzed by a space-trade-for-time experiment. The typical natural successional sequence after fire in Greater Khingan forest is fire-burned land (LG-BA), shrub (SHR), birch forest (BP), mixed forest of larch and birch (BP-LG), and larch forest (LG-OM). 0?10 cm top mineral soil samples were collected on forest plots and the bacterial community structure and diversity were determined with Illumina MiSeq high-throughput sequencing technique. [Results] The number of bacterial species from low to high was in the sequence of the larch and birch mixed forest, shrub forest, larch forest, and birch forest. Following forest succession, the Simpson diversity index firstly increased and then decreased. The Shannon index followed the dynamic trend of increase, decrease and increase pattern. The change of OTU (Operational taxonomic unit) abundance was relatively gentle in the succession processes, indicating that the species change was small. The phyla of soil bacteria were mainly Proteobacteria, Acidobacteria, Actinobacteria and Planctomycetes in all of the successional stages, all of them followed the change trend of increase in the first succession stage and decrease in the later stage. PCA analysis showed that bacterial communities were different in the varied successional stages. RDA analysis showed that organic matter, total nitrogen, total phosphorus and pH impacted soil bacterial community. [Conclusion] Following forest succession, the species of soil bacteria was changed in Greater Khingan forest. The most common soil bacteria communities differed across natural succession, varying as a function of soil SOM, total potassium, total phosphorus, and pH.