[Objective] To screen and identify an endophytic bacterial strain with plant growth-promoting effects on rice from the stem of rice grown in the soda saline-alkaline soil in Daqing City, Heilongjiang Province and explore its plant growth-promoting effects and related genes, with a view to enriching and utilizing the endophytic microbial resources of rice. [Methods] An endophytic bacterial strain was isolated from rice stems via the dilution coating method, and the strain was identified by morphological observation, physiological and biochemical tests, and 16S rRNA gene sequencing. The mechanisms underlying the plant growth-promoting effects of the strain were deciphered by Illumina sequencing of the whole genome. antiSMASH was used to predict the synthetic gene clusters of secondary metabolites. The plant growth-promoting performance of the strain was evaluated by promotion performance, rice seed germination, and seedling cultivation tests. [Results] An isolated endophytic bacterial strain of rice was designated as J-7, and the strain was identified as Acinetobacter baumannii by whole genome sequencing and ANI analysis. The strain was a mesophilic bacterium with an OD₆₀₀ value of 0.679 at pH 10.5, showcasing alkaline tolerance. The strain had an OD₆₀₀ value of 0.293 in the presence of 1.0 mol/L NaCl, exhibiting salt tolerance. The strain had the ability to solubilize inorganic and organic phosphorus, with the amounts of inorganic and organic phosphorus solubilized being (179.54±1.21) mg/L and (65.57±1.07) mg/L, respectively. In addition, the strain had the ability to produce siderophores and utilize ferric ammonium salts. The strain genome (national microbiology data center accession number: NMDC60154488) was 3 666 630 bp in length, with the G+C content of 39% and a total of 3 432 genes (including 8 potential synthetic gene clusters of secondary metabolites). The rice seed germination test results showed that the application of 1×10⁷ CFU/mL suspension of the strain significantly increased the radicle length and stem base width by 13.02% and 17.68%, respectively, compared with the control group. The rice seedling cultivation test results showed that the application of 2×10⁹ CFU/mL suspension of the strain significantly increased the plant height and root length by 32.69% and 36.55%, respectively, compared with the control group. [Conclusion] Strain J-7 has a good growth-promoting effect on rice, showing application potential in agriculture as a microbial strain resource. Whole genome sequencing provides a theoretical basis for in-depth study of the plant growth-promoting mechanism of A. baumannii.