One layer vibration isolation system is usually used in the shock isolation of blast-resistance structures.At the present time

the largest isolation rate can reach 90%.However

the acceleration of the structures after isolation is still very large if the peak acceleration of ground shock is very large.In order to further increase the isolation rate

a double layer vibration isolation system with Magnetorheological fluid dampers（MRD） is investigated numerically in the paper.The double layer vibration isolation system subjected to two typical ground shocks is simulated by Matlab Simulink

based on the modified Bouc-Wen model and fuzzy logic control method.The acceleration

displacement and Vibration Dose Value（VDV） of the structure under two typical ground shocks in different vibration isolation systems are calculated and the comparison of isolation effects between the one layer vibration isolation system and double layer vibration isolation system is given.It is demonstrated that the double layer vibration isolation system with MRD is no better than the one layer vibration isolation system.