Abstract: A wire-winding common mode choke has a body, a first coil and a second coil. The body has two channels respectively defined in two lateral sides of the body and at least two steps. Each step has a first folding end and a second folding end. The first and second coils are wired around the channels of the body and respectively across the first or second folding ends of the corresponding steps. When the first and the second coils are respectively weld by heating, there is no short circuit between the first and the second coils because the steps separate the first and second coils.