A　highly　efficient　damping　control　(HEDC)　device　and　an　active　variable　stiffness/　damping　(AVS.D)　control　device　are　designed　and　manufactured,　and　simulating　earthquake　shaking　table　tests　of　the　two　control　devices　are　carried　out　by　the　authors　of　the　paper　to　examine　their　control　mechanism　and　effectiveness.　The　results　of　the　tests　show　that　(1)　the　control　effectiveness　of　the　HEDC　device　is　significant,　and　it　is　highly　efficient　compared　with　usual　dampers;　(2)　although　a　little　amount　of　energy　is　inputted　into　it,　a　better　control　effectiveness　is　obtained　by　the　AVS.D　control　device;　and　(3)　most　of　the　time,　the　AVS.D　control　device　works　in　variable　damping　state　to　reduce　the　vibration　of　the　controlled　structure.　This　indicates　that　the　influence　of　time　delay　is　small　in　the　device.