To explore effects of histone deacetylase inhibitor Belinostat on the immunologic function of dendritic cells (DC) and its possible mechanism. Cultured mouse bone marrow-derived DC from C57BL/6 mouse . The experiments were divided into 0, 50, 100 nmol/L Belinostat + immature DC (imDC) group, and 0, 50, 100 nmol/L Belinostat mature DC (mDC). The changes of the ultrastructure of DC were observed by transmission electron microscope (TEM). Immunophenotype and CCR7 expression rate were detected by FCM, and the migration rate was observed by chemotaxis assay. The proliferation of lymphocytes stimulated by different DC was detected by mixed lymphocyte culture reaction. The cytokines in the culture supernatant, including TNF-α, IL-12 and IL-10, were examined by ELISA. RQ-PCR was used to examine the relative expression of mRNA in RelB. Successful cultured and identified the qualified imDC and mDC. Belinostat decreased the expression of CCR7 on imDC [(25.82±7.25)% (50.44±5.61)% and (18.71±2.00)% (50.44±5.61)%], meanwhile increased the rate on mDC [(71.14±1.96)% (64.90±1.47)%]. Chemotaxis assay showed that the migration rate of Belinostat+imDC and Belinostat+mDC group were both decreased, but the difference in imDC was not significant. T lymphocyte proliferation rate stimulated by 100 nmol/L Belinostat+imDC group was lower than imDC group in condition irritation cell∶reaction cell=1∶2 [(227.09±13.49)% (309.49±53.69)%]. Belinostat significantly suppressed the secretion of cytokines TNF-α, IL-12 and IL-10 (all <0.01). The relative expression of mRNA in RelB was slightly decreased in Belinostat+imDC and Belinostat+mDC group (all <0.05). Belinostat could effectly suppress DC maturation and regulate immune tolerance of DC, which may be due to the down-regulation of mRNA level of RelB in DC.