Seismic damage data and experiences on power transformers at home and abroad indicate that the destruction type of high-power transformers is various and the vulnerability is very high. Furthermore, the post-disaster reconstruction of transformers, which needs a long recovery cycle and a high cost, will be very difficult. Studies have shown that the acceleration response of the transformer and bushings will be quickly reduced and seismic reliability of transformer will be improved because there is one seismic isolation layer between the bottom of transformer tank and the base which form the seismic isolation system of the transformer and bushings （SISTB）. But isolation layer design and parameters selection of SISTB have larger difference with general structures.