In this study, cabbage and the newly reclaimed field were used as the test materials, a pot experiment was conducted, in which five different biochar dosages (B0, 0%; B5, 0.5%; B10, 1.0%; B20, 2.0%; and B40, 4.0%) were setup, soil physicochemical properties and the growth of cabbage were determined, bacterial community structure and function were explored by high-throughput sequencing technology. The results showed that there were significant variations in cabbage growth and soil physicochemical properties under different treatments. Compared with B0, B10 significantly increased plant height, aboveground biomass and root weight, the contents of soil organic carbon, total nitrogen, available potassium, pH, and CEC, while significantly reducing the root shoot ratio. Biochar treatments (B5, B10, B20, and B40) significantly increased α diversity indices of soil bacterial communities, including Chao 1, Observed species, and Shannon, these diversity indices exhibited significant positive correlations with aboveground biomass and root weight of cabbage, the contents of soil organic carbon, total nitrogen and available potassium, pH, and CEC. Biochar significantly modified the structure of soil bacterial communities by influencing soil properties such as CEC and pH, both bacterial communities and their metabolic functions were strongly associated with aboveground biomass and the root shoot ratio. LefSe analysis indicated that the increase in biochar application promoted the number of key indicator species that contribute to the variations in soil bacterial communities, and many of these species showed significant correlations with cabbage growth metrics. The indicator species identified by were dominantly from bacterial groups such as Bacteroidia and Pseudonocardiaceae under B0, while the indicator species in biochar-treated soils were mainly copiotrophic bacteria, belonging to the phyla Acidobacteriota, Actinobacteriota, Chloroflexi, Myxococcota, and Proteobacteria. The dominant indicator species were Chitinophagales and Blastocatellia under B10, while Alphaproteobacteria, Burkholderiales, and Rhizobiales under B40.Moreover, biochar application had a significant impact on the metabolic functions of soil microorganisms in terms of amino acids, carbohydrates, and lipids. B10 significantly increased the metabolic functions of amino acids and lipids while significantly decreasing the metabolic functions of carbohydrates. In conclusion, biochar application can improve the physicochemical properties of newly reclaimed soil, enrich the bacterial community, and promote crop growth. Considering the cost of application and the amelioration effect, it is recommended to use a biochar dosage of 1.0% for the newly reclaimed fields.