A transformer with high coupling efficiency is composed of base plate, wire-winding axle body and conducting wire unit. Said base plate has multiple welding pads used for electric connections betweenfront and back surfaces, and multiple lower conducting wires on its back for connecting two welding pads. Said wire-winding axle body is used for high-voltage conducting wires. Said conducting wire unit on said wire-winding body has multiple upper conducting wires connected to welding pads. Said upper and lower conducting wires are connected with each other to form a low-voltage loop.