Objective:To investigate the effect of miR-217 on sepsis induced lung injury in rats. Methods:75 SD healthy male rats (SPF grade) were randomly divided into normal group, sham operation group, model group, mir-217 MICs control group, mir-217 MICs control group and mir-217 MICs group. The rats in model group, mir-217 MICs control group and mir-217 MICs group were used to establish sepsis lung injury model by CLP Vein injection of 10 μ L mir-217 MICs control, 10 μ L mir-217 mics, normal group, sham operation group, model group, tail vein injection of normal saline volume. The pathological changes, wet / dry weight (w / D), arterial blood gas, TNF -α, IL-6, IL-1 β, MPO, PMN cell count, mir-217, TLR4 Signal pathway protein expression were evaluated.Results:The pathological scores, W/D, pH and BE of the mir-217 mimics group were all lower than that of the mir-217 mimics control group, while the PaO2 was higher than that of the mir-217 mimics control group, with statistically significant differences (P ＜ 0.05). The levels of TNF -α , IL-6, IL-1 and MPO in serum and alveolar lavage fluid of the mir-217 mimics group were lower than those of the mir-217 mimics control group, with statistically significant differences (P ＜ 0.05). The protein content and PMN cell count in the alveolar lavage fluid of the mir-217 mimics group were lower than that of the mir-217 mimics control group, with statistically significant differences (P ＜ 0.05). The expression level of mir-217 in the lung tissues of the mir-217 mimics group was higher than that of the mir-217 mimics control group, and the expression level of TLR4 signaling protein in the lung tissues of the mir-217 mimics control group was lower than that of the mir-217 mimics control group, with statistically significant differences (P ＜ 0.05).Conclusion:Mir-217 overexpression can inhibit TLR4 Signal transduction pathway, block inflammatory response, improve lung injury caused by sepsis and protect lung tissue.