Objective:To investigate the effects of icariin (ICA) on the phenotype of interleukin-1β (IL-1β)-induced inflammatory chondrocytes. MethodsThe articular chondrocytes of rats were isolated and cultured. The primary chondrocytes were induced by IL-1β,and the inflammatory environment of chondrocytes in osteoarthritis was simulated. The cells were divided into the blank group,model group(treated with IL-1β at concentration of 10 mg/L),ICA group with low-concentration(treated with IL-1β at concentration of 10 mg/L and ICA at concentration of 1 μmol/L)and ICA group with high-concentration(treated with IL-1β at concentration of 10 mg/L and ICA at concentration of 5 μmol/L).The protein expressions of collagen-II and aggrecan were detected by Western blot. The mRNA expressions of collagen-II,aggrecan,matrix metallopeptidase-13(MMP-13)and a disintegrin and metalloprotease with thrombospondin motifs-5(ADAMTS-5)were detected by RT-PCR.  Results:After the cells were cultured for three day,compared with the model group,ICA could obviously promote the mRNA and protein expressions of collagen-II in the inflammatory chondrocytes(P<0.05)；and this effect in the ICA group with high-concentration was more significant than that in the ICA group with low-concentration(P<0.05). Compared with the model group,ICA could obviously promote the mRNA and protein expressions of aggrecan in the inflammatory chondrocytes(P<0.05)；and this effect shows no obviously difference between the low- and high-concentration. Compared with the model group,ICA could inhibit the mRNA expressions of MMP-13 and ADAMTS-5(P<0.05),and the inhibiting effect on MMP-13 mRNA expression was more significant in the ICA group with high-concentration(P<0.05)；there was no obvious difference on the ADAMTS-5 mRNA expression between the low- and high-concentration.  Conclusion:ICA can inhibit the expressions of MMP-13 and ADAMTS-5 and promote the expressions of collagen-II and aggrecan in the inflammatory chondrocytes,and thus maintain the chondrocytes phenotype and promote the matrix metabolism.