Objectives:To investigate the antibacterial effects of Acinetobacter baumannii on Acinetobacter SPP. Methods:A Acinetobacter baumannii strain named SL- A.baumannii that can inhibit other Acinetobacter baumannii strains was isolated from the bronchoalveolar lavage fluid of a critically infected patient in the department of neurology, Henan Provincial Hospital on December 10, 2020. To better understand this inhibition effect, the drug resistance, homology and protein fingerprint of the new Acinetobacter baumannii strain, along with 40 other Acinetobacter SPP isolates, were analyzed. Results:Multilocus sequence typing (MLST) revealed that a novel allele combination (gltA/gyrB/gdhB/recA/cpn60/gpi/rpoD) 33, 12, 40, 26, 48, 54, 5 was found in SL- A.baumannii, and ST-2442 was assigned by PubMLST (Oxford). Moreover, 36 isolates, including 30 Acinetobacter baumannii strains, 2 Acinetobacter lwoffii strains, 3 Acinetobacter pittii strains and 1 Acinetobacter ursingii strain, were inhibited by SL- A.baumannii, the inhibition rate was 90% (36/40). Among those strains, 18 (50%) were sensitive to all the antibacterial drugs; 16 (44.44%) showed multi-drug resistance(MDR), including 2 pan-drug resistance(PDR) and 11 extensive drug resistance (XDR) strains; the other 2 (5.56%) were only resistant to Trimethoprim/Sulfamethoxazole(SXT). Conclusion:The new sequence type (ST-2442) Acinetobacter baumannii isolate SL- A.baumannii (PubMLST/Acinetobacter baumannii isolates database/id: 6942) had shown a significantinhibitory effect on Acinetobacter SPP with different drug-resistant phenotypes.