The invention belongs to the technical field of fusion reactor penetration piece, and more specifically relates to a tandem-type electrically-charged waterway penetration piece used on fusion reactorvacuum side. According to the tandem-type electrically-charged waterway penetration piece used on fusion reactor vacuum side, a first layer electrical isolation constraint structure and a second layerelectrical isolation constraint structure are connected and communicated through a separating sleeve in series to form an electrical isolation constraint structure; an ITER flange is of a circular disc structure; the center of the ITER flange is provided with a through hole; a flange pipe is of a cylindrical structure, and is designed to pass through a through hole at the center of the ITER flange center; the ITER flange is welded at flange pipe middle segment; flange pipe right segment is designed to stretch into atmosphere side; a CP flange is provided with a plurality of bolt holes, ITER flange fastening bolts are designed to pass through the plurality of bolt holes on the CP flange for installation of the ITER flange on constrain barrier CP flange vacuum side; the right end of the flange pipe is provided with a guide metal pipe; the electrical isolation constraint structure is arranged in the flange pipe; an electrically-charged water pipe is designed to pass the guide metal pipefrom right to left successively; and the first layer electrical isolation constraint structure and the second layer electrical isolation constraint structure are designed to stretch out from the flange pipe and stretch into the vacuum side.