In this study,Chinese Holstein mammary epithelial cells(DCMECs)were used as a model to investigate the effects of miR-223 on DCMECs inflammation and milk fat synthesis induced by lipopolysaccharide(LPS).Western blot was used to detect the expression of Tumor necrosis factor-α(TNF-α)and Fatty acid synthase(FASN).miR-223 was transfected into DCMECs,qRT-PCR by liposome transfection tech-nique to detect the relative expression of miR-223.In situ fluorescence technique was used to detect the apoptosis and milk fat synthesis of DCMECs.The results showed that the best concentration of LPS to induce DCMECs inflammatory reaction was 1 μg/mL;adding LPS could promote the expression of DCMECs miR-223;after DCMECs transfection into miR-223,the expression of miR-223 was significantly up-regulated;miR-223 could down-regulate the inflammatory protein TNF-α of DCMECs induced by LPS,up-regulate the protein FASN relat-ed to milk fat synthesis,inhibit LPS-induced apoptosis and promote LPS-induced milk fat synthesis.