The　paper　aims　to　develop　an　innovative　system　to　improve　the　performance　of　the　traditional　AVS　system,　which　bears　the　disadvantage　of　limited　narrow　bandwidth　frequency-adjustment　capability.　The　deficiencies　of　the　traditional　AVS　system　were　analyzed　by　using　seismic　response　spectra.　Then　an　innovative　semiactive　continuously　variable　stiffness　(SCVS)　system　was　presented　and　its　performance　and　effectiveness　were　illustrated　by　numerical　examples.　It　is　demonstrated　that,　compared　with　the　traditional　AVS　system,　the　adjustable　frequency　bandwidth　of　the　proposed　system　is　significantly　increased,　and　the　displacement　and　the　acceleration　responses　of　the　structure　are　further　decreased　simultaneously.