Wireless　sensor　is　one　of　key　components　of　on-line　monitoring　system　for　high-voltage　electrical　equipment　(HV-EE).　Moreover,　highly　reliable　power　supply　is　the　key　technology　for　further　development　and　applications　of　the　sensors　equipped　in　the　on-line　monitoring　systems.　Firstly,　we　proposed　a　scheme　of　the　contactless　power　supply　via　magnetic　resonance　(MR-CPS)　for　powering　the　sensor　and　the　associated　sensor　solution.　The　key　specifications　of　the　MR-CPS　were　defined　by　applications　in　switchgear　cabinet　under　a　harsh　operation　environment　of　multiple　metal　components.　Secondly,　by　mutual　inductance　modeling,　we　introduced　design　key　parameter　kQ　of　magnetic　resonant　unit　(MRU)　in　the　MR-CPS,　and　put　forward　a　method　of　optimizing　the　resonant　windings　with　finite　element　simulation.　Finally,　a　prototype　was　built　and　tested.　In　the　experiments,　the　prototype　was　tested　under　high　voltage,　high　current,　and　metal　components,　respectively,　to　simulate　the　actual　operation　environment.　The　experimental　and　operation　results　show　that　the　MR-CPS　is　able　to　deliver　the　rated　output　power　0.5　W　at　3.3　V　with　maximum　efficiency　32%,　and　has　good　aplication　for　the　switchgear　cabinet　with　up　to　20　kV　and　1　kA.　The　researches　show　that　MR-CPS　not　only　can　be　installed　easily,　but　also　supplies　the　reliable　power　to　the　sensor;　and　the　kQ　should　be　increased　in　order　to　improve　the　transmission　efficiency.　©　2017,　High　Voltage　Engineering　Editorial　Department　of　CEPRI.　All　right　reserved.