Abstract: Objective To investigate the percentage of T helper 17 (Th17) and miR-155 level in peripheral blood of rats with sepsis caused by Acinetobacter baumannii, and explore their relationships. Methods Total 32 clean SD rats were randomly divided into normal control group (N group), and 6 h, 12 h and 24 h sepsis group, with 8 rats in each group. The sepsis rat model was established by intraperitoneal injection with Acinetobacter baumannii suspension, while the rats in N group were injected with normal saline. The serum and lymphocyte were separated from peripheral blood of rats. The fluorescence quantitative rt-PCR was used to detect expression of miR-155. Flow cytometry was used to detect the ratios of Th17 cells over CD4⁺ T cells in peripheral, enzyme-linked immunosorbent assay (ELISA) was used to measure the serum level of interleukin-10 (IL-10). The difference among N group and 6 h, 12 h and 24 h sepsis group were analyzed. Pearsons correlation analysis was used to evaluate the relationship between miR-155 and Th17. Results Serum level of miR-155 was significantly higher in rats with sepsis than that in normal group (all P<0.05). Th17 cells was significantly higher in rats with sepsis than that in normal group (all P<0.05). Pearsons correlation analysis showed that the serum level of miR-155 was positively correlated with Th17 cells (all P<0.05). Conclusion The expression of Th17 and miR-155 is increased in Acinetobacter baumannii sepsis rats. The serum level of miR-155 is positively correlated with Th17 cells, which can used as the target in the early diagnosis and treatment of Acinetobacter baumanni.