Aim To investigate the effect and mechanism of retinoid X receptor agonist 9-cis retinoid acid on the differentiation of macrophage into dendritic cell induced by LPS. Methods LPS-treated RAW264.7 murine macrophage cell line differentiated into dendritic like cells after 48h. The effect of 9-cisRA on the differentiation induced by LPS was studied. Cell morphology was observed by phase contrast microscope and cell surface markers involved in dendritic cell immune maturation and activation (CD40, CD86, CD83) was analyzed by FACS. Cellular reactive oxygen species production was detected by CM-H2DCFDA fluorescent probe. Results 9-cisRA partly prevented dendritic like morphology induced by LPS. Upregulated cell surface markers CD40、CD86 and CD83 by LPS were decreased about 50%、40% and 38% respectively by 9-cisRA. And the effect of 9-cisRA was dose dependent. LPS-treated RAW264.7 acquired significantly increasing cellular reactive oxygen species (MFI 98.9±9.6 vs 12.3±1.8,p<0.05), which was significantly reduced by 9-cisRA at 10-8M and 10-7M to 69.4±5.8 and 37.0±4.2 respectively. Conclusion RXR agonist 9-cisRA partly inhibits the differentiation of macrophage into dendritic cell induced by LPS, which may be related to reducing oxidative stress injury.