〔Abstract〕 Objective To explore the molecular mechanism of lipopolysaccharide(LPS) on the contraction of pregnant uterine smooth muscle at tissue and cellular levels. Methods C57BL/6J mice at 16 days of gestation were randomly divided into control group and LPS group. The mice in LPS group were intraperitoneally injected with 20 μg in LPS solution to establish the model of preterm birth, and the mice in control group were intraperitoneally injected with the same amount of normal saline. Isolated uterine muscle strips were used to detect changes in the contractile function of the tissue, as well as changes in the expression and function of the contraction key signaling molecule TWIK-related K+channel 1(TREK-1). Primary cultured pregnant mouse uterine smooth muscle cells were used to detect the expression of TREK-1 under the regulation of LPS. Results The contractility of mouse uterine tissues was significantly enhanced by LPS, and the protein expression of TREK-1, a key signal for contraction, was significantly reduced, and activation of TREK-1 resulted in a significant down-regulation of the enhanced contractility of mouse uterine tissues in the LPS group. However, there was no significant difference in the expression of TREK-1 protein, which was highly expressed in the smooth muscle of pregnant mice, when LPS acted on the primary uterine smooth muscle cells of pregnant mice. Conclusion Uterine contractility is enhanced in pregnant mice uterine tissues by inhibiting TREK-1 expression and function in response to LPS, and it may be one of the mechanisms by which LPS induces preterm labor. However, the effect of LPS on TREK-1 on mouse pregnant uterine smooth muscle cells may be realized through intercellular signaling and not directly on uterine smooth muscle cells. This further suggests that the animal and histological experiments cannot be completely replaced by isolated cell experiments in the study of inflammatory preterm labor.