This paper presents the design process of a magnetorheological elastomer (MRE) absorber with a shear symmetric structure based on detailed simulation and experiments. First, the MRE materials and dimensional parameters of the MRE absorber are determined, and magnetic field simulation is performed to analyze the magnetic induction performance in the working area. Then, a dynamic simulation model is constructed to analyze the frequency response characteristics of a semi-active vibration system. Finally, a vibration experimental platform is built to test the response performance of the shear-mode MRE absorber. The experimental results showed that the stiffness of the MRE absorber can be effectively adjusted by current. When the applied current changes from 0.5 to 2 A, a vibration reduction frequency band of 8.91 to 14.19 Hz will be formed. The closer the natural frequency in this frequency band is to the external excitation frequency, the better the vibration reduction effect, which verifies the effectiveness of semi-active vibration control for the primary system. These results validate the rationality and feasibility of the semi-active MRE absorber, providing a good reference for the design of MRE absorbers.