Plant growth-promoting bacteria (PGPB) can improve plant growth and play a major role in the development of plants. The present study was concerned with a PGPB (defined as JX14) isolated from calcareous alluvial soil and was analyzed for its plant growth-promoting effect on peanuts. The nitrogenase activity of JX14 was C2H4 38.9 nmol/(h·ml), the transformation amounts of tricalcium phosphate was 96.19 mg/L. Strain JX14 was identified as Variovorax sp. (GenBank Accession No. JX424612) based on the morphological, physiological and biochemical characteristics and 16S rRNA gene sequences analysis. In pot experiments, compared to the non-inoculated treatment, inoculation with JX14 significantly increased soil NH₄⁺ -N, NO₃^– -N, mineral N and available phosphorus concentrations by 1.08, 1.18, 1.16-fold and 18.14%, which led to 1.61, 1.28, 1.37, 1.12-fold significant increases in the root length, surface area, root volumes and root tips of peanuts, respectively. In addition, plant morphological characteristics such as wet weight and height significantly increased by 44.78% and 14.10%, and plant nutrient content such as total N, total P and total K of peanuts significantly increased by 35.14%, 171.43% and 133.33%, respectively. The IAA-producing bacterial strain JX14 has promising application in promoting plant growth in peanuts production.