In　summary,　there　are　two　main　issues　facing　high　voltage　parameter　online　measurement:　obtaining　of　high-voltage　side　working　power,　and　signal　transmission　between　high　and　low　voltage.　To　resolve　these　issues,　we　propose　and　design　the　high　voltage　parameter　online　measurement　sensor　system　whose　light　source　and　light　signal　transmission　is　based　on　a　sealed　space.　The　sensor　system　contains　high-voltage　side　power　supply　system　and　signal　measurement　and　transmission　system　that　are　sealed　inside　a　layer　insulator.　The　sealed　light　source　and　signal　transmission　makes　sure　the　high　efficiency　and　reliability　of　power　source　at　high-voltage　side　signal　sampling　and　processing　circus.　It　also　guarantees　the　safety,　reliability　and　accuracy　of　signal　transmission.　This　article　introduces　the　working　principle,　the　structure　and　the　design　of　the　sensor　system.