Passive　negative　stiffness　dampers　(NSDs)　possess　significant　advantages　and　promising　application　prospects　in　the　field　of　structural　vibration　control.　NSDs　with　high　energy　dissipation　capability　are　desired　to　satisfy　the　vibration　mitigation　requirements　for　large-scale　engineering　structures,　such　as　high-rise　buildings　and　long-span　bridges.　However,　in　practical　applications,　due　to　the　constraints　of　mounting　space　and　additional　weight,　the　negative　stiffness　and　damping　coefficient　of　existing　NSDs　are　generally　not　very　large　and　with　poor　adjustability.　To　overcome　these　limitations,　this　study　develops　a　novel　magnetic　negative　stiffness　eddy-current　damper　(MNSECD)　with　enhanced　overall　performance.　This　damper　consists　of　a　magnetic　negative　stiffness　system　(MNSS),　a　multi-layer-plate-type　eddy-current　damping　system　(ECDS)　in　parallel,　and　a　bidirectional　ball　screw　transmission　system.　Firstly,　different　magnetic　arrays　are　designed　to　optimize　the　magnetic　fields　of　the　MNSECD,　and　to　enhance　its　magnetic　negative　stiffness　and　eddy-current　damping　without　adding　extra　dimensions　and　weight.　Subsequently,　the　electromagnetic　finite-element　models　(FEMs)　of　the　MNSECD　are　established　to　precisely　simulate　its　magnetic　negative　stiffness　and　eddy-current　damping　forces,　and　these　models　are　further　utilized　to　elucidate　the　enhancement　mechanism　of　different　magnetic　arrays.　Finally,　based　on　the　numerical　simulation　results,　the　best　performing　magnetic　array　is　selected　respectively　for　the　ECDS　and　MNSS　systems　to　carry　out　experimental　studies　on　a　small-scale　prototype.　Numerical　and　experimental　results　indicate　that　the　selected　magnetic　array　for　the　MNSS　proves　highly　effective　in　enhancing　the　magnetic　negative　stiffness　of　the　MNSECD,　while　the　selected　magnetic　array　for　the　ECDS　also　demonstrates　superior　effectiveness　in　enhancing　the　eddy-current　damping　of　the　damper.　These　findings　suggest　that　the　novel　MNSECD　can　be　readily　used　in　the　vibration　control　of　large-scale　engineering　structures.