Aim To investigate the effect of proprotein convertase subtilisin/kexin 9(PCSK9) siRNA on inflammatory factor expression in oxidized low density lipoprotein(ox-LDL) induced THP-1 macrophage cells. Methods The siRNAs for PCSK9 were designed and synthesized,then THP-1 macrophages were transfected with 80 nmol/L PCSK9 siRNA by positive ion liposome Lipofectamine 2000 for 24 h and then a high level of ox-LDL(80 mg/L) for an additional 24 h.Reverse transcription polymerase chain reaction(RT-PCR) was conducted to detect interleukin-1α(IL-1α) mRNA,interleukin-6(IL-6) mRNA and tumor necrosis factor-α(TNF-α) mRNA. Results Ox-LDL increased IL-1α mRNA,IL-6 mRNA and TNF-α mRNA expression.The expression of IL-1α mRNA,IL-6 mRNA and TNF-α mRNA in the macrophage pretreated with PCSK9 siRNA was decreased significantly,in comparison with ox-LDL-treated group(P<0.05). Conclusion PCSK9 siRNA can repress inflammation factor expression of THP-1 macrophage cells induced by ox-LDL.PCSK9 may be involved in adjustment for inflammation.