Abstract: [ Objective ] The effects of DNA methyltransferase 1 （DNMT1） on the apoptosis of fibroblast-like synovial cells （FLS） in rheumatoid arthritis（RA）model rats were studied. [Method] The expression of DNMT1 in RA model rats and control rats was detected by using Real-time qPCR. And the effects of siRNA transfection of DNMT1 on the expression of anti-apoptosis gene Bcl-2 were studied. The effects of siRNA transfeetion of DNMT1 on the proliferation of FLS were detected by MTY. [Result] Compared with control group, the expression of DNMT1 in FLS of RA model rats was significantly up-regulated. After the expression of DNMT1 was inhibited,the expression of Bcl-2 was significantly down-regulated. The results of MTF detection showed that the proliferation activity of FLS was significantly reduced after the inhibition of DNMT1 expression. [ Conclusion ] The inhibition of DNMT1 expression might lead to the apoptosis of FLS in RA model rats.