〔Abstract〕 Objective To investigate the effect of aryl hydrocarbon receptor(AhR) on the proliferation and chondrogenic differentiation of human umbilical cord derived mesenchymal stem cells(hUC-MSCs). Methods The h UC-MSCs were transfected with AhR-homo-1432 inhibitor and AhR-homo-1432 inhibitor negative control,and set as si-NC group and si-AhR group. The proliferation ability of hUC-MSCs were measured by CCK-8 assay on day1,3,5 and 7 after transfection. Real-time quantitative PCR and Western blot were used to detect the mRNA and protein expression of chondrogenic marker SOX-9 and COL2 A1 after 7 days of the chondrogenic differentiation. Alcian blue staining was used to detect the expression of proteoglycan. Results Compared with si-NC group,the mRNA and protein expression of AhR in si-AhR group decreased which indicated the transfection of hUC-MSCs was successful. The results of CCK-8 showed that compared with si-NC group,the cell viability of si-AhR group improved on 5 and 7 day. After induction of chondrogenic differentiation,the results showed that compared with si-NC group,the expression of SOX-9 and COL2 A1 in si-AhR group increased and Alcian blue staining showed that the siAhR group had more proteoglycan contents,deeper staining and stronger cartilage differentiation ability. Conclusion Knocking down the expression of AhR can promote the proliferation and chondrogenic differentiation of h UCMSCs