Magnetorheological elastomer(MRE)is the solid analog of MR fluid，there are several problems limit the practical application of MRE，such as low MR effect. According to the fact that carbon content of carbonyl iron powder(CIP)affect the maximum permeability of CIP，this paper studies the influence of carbon content of CIP on MR effect of MRE. The MRE samples are fabricated by silicone rubber and CIP with different carbon content. A dynamic mechaical analyzer is modified to characterize dynamic mechanical properities of MRE samples. Experimental result shows MR effect has an increasing tendency with the decreasing of carbon content.