Objective To explore the effects of TLR4 on Acinetobacter baumannii (A. baumannii) infection in a rat model. Methods Healthy male SD rats were divided into normal control group, TAK-242 treated group, A. baumannii treated group, TAK-242 and A. baumannii combined treatment group. Rats of TAK-242-treated group were prepared by caudal vein injection of TAK-242 (1 mg/kg). A. baumannii were isolated from intensive care unit (ICU) and the freshly grown bacteria (1×108 CFU/mL) were prepared. Each normal or TAK-242-treated rat was inoculated with 50 μL A. baumannii through trachea. The bronchoalveolar lavage fluid (BALF) and blood were collected at 72 hours after inoculation. The histopathology of lung was evaluated by HE staining. TNF-α and IL-6 were detected by ELISA. The level of phosphorylated NF-κBp65 (p-NF-κBp65) in peripheral blood mononuclear cells (PBMCs) was detected by Western blot analysis. Results A. baumannii were eliminated within 72 hours in normal rats, whereas bacteria continued to replicate rapidly in the lungs of TAK-242 A. baumannii treated group. The pulmonary inflammatory was more severe than the normal rats. The levels of TNF-α and IL-6 increased markedly after the infection. However, the levels of TNF-α and IL-6 in the TAK-242 combined with A. baumannii treated group were lower than those in the A. baumannii treated group. The level of p-NF-κBp65 increased significantly in the PBMCs of the normal rats 72 hours after infected with A. baumannii, but increased slightly in the TAK-242 combined with A. baumannii treated group. Conclusion TLR4/NF-κB pathway plays an important role in the process of A. baumannii infection, and TLR4 can be used as a target molecule in the treatment of A. baumannii infection.