Wireless　sensor　is　the　key　component　to　promote　the　development　of　smart　grid,　and　its　power　supply　has　attracted　much　attention.　Present　power　supply　schemes　are　mainly　concerned　about　battery　and　energy　harvester,　but　battery＇s　life　is　short,　and　most　off-the-shelf　energy　harvester　have　significant　limitation　in　the　applications　smart　grid.　A　small　volume　and　high　performance　magnetic　core　structure　was　proposed　according　to　the　structure　character　of　switch　cabinet　bus-bar　of　power　grid,　and　a　tank　circuit　was　designed,　based　on　the　principle　of　resonance,　to　improve　the　whole　system　load　capability.　Simulation　analysis　and　prototype　test　have　verified　the　effectiveness　of　the　proposed　energy　harvester　structure.　©　2020　Chin.　Soc.　for　Elec.　Eng.