Objective To study the application of Bacillus velezensis D44 in the biological control of postharvest diseases in peaches.Methods Hu nectarine 018 (hard-soluble), Jinxiu yellow peach (hard-soluble), and Hujing Milu honey peach (soft-soluble) were used as test materials. The antagonistic effects of B. subtilis A9, B. velezensis D44, and B. licheniformis W10 against seven postharvest pathogens-Polyporus pink, Penicillium, Fusarium, brown rot fungus, Botrytis cinerea, Alternaria alternata, and Rhizopus-were examined. Additionally, the impact of these bacteria on the diameter of disease lesions, volatile substances, and preservation effects in peach fruits after inoculation with these pathogens was evaluated.Results B. velezensis D44 exhibited strong inhibitory effects on brown rot fungus, Rhizopus, B. cinerea, Penicillium, and Fusarium in peaches. At room temperature, the onset of brown rot in Hu nectarine 018 and Hujing Milu peaches inoculated with brown rot fungus was delayed by 2 days compared with the control, with an inhibition rate of 85% to 99%. The onset of soft rot in Hu nectarine 018 and Hujing Milu peaches inoculated with Rhizopus was delayed by 3 days compared with the control, with a disease inhibition rate of 87.61% to 99.82%. B. velezensis D44 also significantly inhibited the changes in volatile substances caused by decay. The safe storage period of Hu nectarine 018 treated with D44 at room temperature was 6~8 days, which was 4~6 days longer than the control, with a decay rate of less than 5%, a weight loss rate below 4.5%, and a decline in soluble solids controlled within 8%. The safe storage period of Hujing Milu peaches at room temperature was 4~6 days, which was 2~4 days longer than the control, with a decay rate below 8%, a weight loss rate below 8%, and a decline in soluble solids controlled within 4%. The treated fruits exhibited high commercial and edible value.Conclusion B. velezensis D44 significantly delays the onset of brown rot and Rhizopus and effectively preserves the storage quality, thereby extending the shelf life.