Objective To explore alleviation of the inflammatory response induced by acute lung injury in sepsis rats by down-regulation of miR-128-3p and effects on lung tissue morphology. Methods Sixty healthy 3-week-old SD rats were divided into a sham-operated group, a sepsis model group, a blank transfection group and an miR-128-3p inhibitor group by a random grouping method with 15 rats in each group. Sepsis models were prepared by cecal ligation and puncture. In the blank transfection group, blank plasmids were constructed and were transfected into rats. In the miR-128-3p inhibitor group, lentiviral plasmids were constructed and were transfected into rats. The expression of miR-128-3p was detected by RT-PCR to determine the success of interference. Resting ventilation, changes in airway resistance and lung volume were determined in each group. The contents of serum IL-6, TNF-α and iNOS in peripheral blood were detected by ELISA. Lung tissues and pathological injury were observed by hematoxylin & eosin ( HE) staining. The expression of Caspase-3 and Caspase-9 in lung tissue was detected by TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) staining and western blotting. The expression of TGF-β and α-SMA was detected by Masson 's trichrome staining and western blotting. Results HE staining showed that cell distribution was even in the miR-128-3p inhibitor group, with few necrotic cells. MASSON staining showed that there was severe fibrosis and damage of lung tissues in sepsis model group, and degree of lung tissue fibrosis in miR-128-3p silencing group was improved. Compared with the sham-operated group, expression of miR-128-3p, airway resistance, levels of IL-6, iNOS and TNF-α, apoptosis rate of lung tissue cells, relative expression of cleared cas3 / Caspase-3, cleared cas9 / Caspase-9, and TGF-β and α-SMA protein levels were significantly increased (P< 0.05), while resting ventilation, changes in airway resistance and lung volume were significantly decreased in the sepsis model group (P<0.05). Compared with the blank transfection group, expression of miR-128-3p, airway resistance, levels of IL-6, iNOS and TNF-α, apoptosis rate of lung tissue cells, relative expression of cleared cas3 / Caspase-3, cleared cas9 / Caspase-9, and TGF-β and α-SMA protein levels were significantly decreased ( P < 0. 05), while resting ventilation, changes in airway resistance and lung volume were significantly increased in the miR-128-3p inhibitor group (P<0.05). Conclusions Down-regulation of miR-128-3p can alleviate acute lung injury in sepsis rats and the mechanism of action may be related to a reduced inflammation response and inhibited apoptosis of lung tissue cells.