In order to explore the feasibility of magnetorheological elastomer (MRE) used in variable stiffness semi-active vibration isolation，silicone rubber based MRE was prepared; the MRE isolator was designed and manufactured; the MRE material and the performance of the isolator were tested; the variable stiffness semi-active vibration isolation system based on MRE isolator was built，and the on-off control，fuzzy control and GA fuzzy control algorithms were designed. The test results show that the storage modulus of MRE reaches saturation when the magnetic induction intensity is 600 mT，and the magnetorheological effect reaches more than 2 000%; the variable stiffness characteristic of MRE isolator is obvious，when the coil current changes from 3 A to -3 A，and the equivalent stiffness increases from 74.216 kN/m to 137.128 kN/m with an increase of 84.8%. After optimization，the GA fuzzy control effect is improved by more than 10%，and the control effect of the three methods on the peak value of displacement response is more than 50%，and the control effect on the RMS value of displacement is more than 60%. The results show that the effect of GA fuzzy control is obviously improved after optimization，and the magnetorheological elastomer vibration isolator can be effectively applied to the semi-active vibration isolation control system with variable stiffness.