A winding structure includes a coil having a wire wrap and two wire tails, and a magnetic core having a center column, a flange, four wire-hanging parts and two bosses; the center column is connected at a top surface of the flange, the first boss is disposed in the middle of a first side of the flange, and the second boss is symmetrical to the first boss; transition surfaces of wire-hanging parts to a bottom surface of the flange are chamfered surfaces; first to fourth sections of the first wire tail are sequentially attached to the first wire-hanging part and the first chamfered surface, the bottom surface of the flange, the third chamfered surface, the third wire-hanging part, and the top surface of the flange; first to fourth sections of the second wire tail are symmetrical to first to fourth sections of the first wire tail, respectively.