Mega-sub　structures　based　on　the　sub-structure　isolation　can　solve　the　problem　of　height-width　ratio　limitation　of　the　base　isolated　high-rise　structures.　The　existing　studies　mostly　focus　on　the　theoretical　and　numerical　analysis　of　the　mega-sub　structure　under　far-field　ground　motions.　An　experimental　model　of　mega-sub　structure　was　designed　and　manufactured,　which　had　three　mega　floors.　Lead　rubber　bearings　were　installed　at　the　bottom　of　the　sub-structure,　then　comparison　shaking　table　tests　of　the　uncontrolled　and　controlled　mega-sub　structure　under　near-field　and　far-field　ground　motions　were　performed.　The　results　showed　that　setting　isolation　layer　at　the　connection　between　the　sub-structure　and　the　main-structure　had　obvious　damping　effect　of　Tuned　Mass　Damper　(TMD)　on　the　main-structure＇s　seismic　responses　and　significant　isolation　effect　on　the　sub-structure＇s　seismic　reactions.　The　seismic　responses　of　the　main-structure　and　the　sub-structure　under　near-field　ground　motions　are　bigger　than　that　under　far-field　ground　motions.　Under　strong　near-field　ground　motion,　there　is　pounding　between　isolated　sub-structures　and　main-structure,　which　has　disadvantages　towards　structure＇s　degree　of　comfort　and　safety.　©　2017,　Engineering　Mechanics　Press.　All　right　reserved.