Objective To investigate the effect of matrix metalloproteinase（MMP）11 on the proliferation and collagen synthesis of human aortic（HA）⁃ vascular smooth muscle cells（VSMC）induced by transforming growth factor β1（TGF⁃β1）. Methods The experimental groups were as follows：the control group，0.1，1，5， 10 ng/mL group（0.1，1，5，10 ng/mL TGF⁃β1），5 ng/mL+si⁃NC group（5 ng/mL TGF⁃β1+transfected si⁃NC）and 5 ng/mL+si⁃MMP11 group（5 ng/mL TGF⁃β1+transfected si⁃MMP11）. Western blotting，MTS and RT⁃qPCR assay were conducted to detect the expression of cyclin D1（CyclinD1），PCNA，Collagen Ⅰ，Collagen Ⅲ and MMP11， respectively. Results In 0.1，1，5，and 10 ng/mL TGF⁃β1⁃treated HA⁃VSMC，CyclinD1，PCNA，Collagen Ⅰ， Collagen Ⅲ and MMP11 expression，as well as proliferation activity were higher than those in the control group （P < 0.05，respectively）. The protein level of CyclinD1，PCNA，Collagen Ⅰ and Collagen Ⅲ，and proliferation activity in HA⁃VSMC in 5 ng/mL TGF⁃β1+si⁃MMP11 group were lower than those in 5 ng/mL+si⁃NC group（P < 0.05，respectively）. Conclusion MMP11 was highly expressed in HA⁃VSMC induced by TGF⁃ β1 at different concentrations. Knock⁃down of MMP11 could reverse the effect of TGF⁃β1 on proliferation and collagen synthesis in HA⁃VSMC.