Abstract: Objective To observe the effect of the medium-chain fatty acid octanoic acid (C8:0) on the expression of ABCA1 and JAK2/STAT3 inflammatory pathway in RAW264.7 macrophages. Methods Fatty acids with different concentrations were used to establish different experiment groups:negative control group,C8:0 group,C16:0 group and cAMP group.After 24 hours of intervention in RAW264.7 macrophages,relative expression of ABCA1 mRNA and JAK2/STAT3 pathway-related mRNA was detected by Reverse Transcription-Polymerase Chain Reaction (RT-PCR),relative level of ABCA1/JAK2/ STAT3 pathway-related protein was detected by western blot (WB),and TNF-ɑ,IL-6 and MCP-1 were detected by enzyme linked immunosorbent assay (ELISA). Results The relative expressions of ABCA1 mRNA and protein in RAW264.7 macrophages were significantly higher at C8:0 200μmol/L than those at 100μmol/L (P<0.05).At the concentration of 200μmol/L,compared with the negative control (NC) group,the relative mRNA expression levels of ABCA1 and STAT3 in C8:0 group significantly increased,while the relative mRNA expression levels of P65 decreased significantly (all P<0.05).Meanwhile,the relative expression levels of ABCA1,p-STAT3 and p-JAK2 in the C8:0 group increased significantly,while the relative expression levels of P65 decreased significantly (all P<0.05).The inflammatory factor level of TNF-ɑ in C8:0 group was significantly lower than that in negative control group,the level of IL-6 was significantly lower than that in cAMP group,and the level of MCP-1 was significantly lower than that in EPA group (all P<0.05). Conclusion C8:0 can inhibit inflammatory expression by up-regulating ABCA1 and inhibit JAK2/STAT3 pathway in RAW264.7 macrophages.