An improved compact twin-shaft bobbin structure includes penetrating first and second center through-holes on first and second bobbins, respectively. First and second winding slot groups having a plurality of adjacent respective first and second winding slots are provided on the outer peripheral sides of the first and second center through-holes, respectively. First and second receiving recesses laterally extend from ends of the first and second center through-hole, respectively. First and second pin groups and an opening are provided on ends of the first and second receiving recesses, respectively. Two clamping slots are provided on the top and bottom of the second winding slot group, respectively. A shield in the shape of an "n" is provided on one side of the second bobbin. The shield includes bent flanges along two edges thereof. The two flanges are inserted into the two clamping slots, respectively to fasten the shield to the second bobbin. When the first and second bobbins are juxtaposed with their openings adjacent to each other, the first and second receiving recesses are in communication with each other, while the first and two center through-holes extend in parallel to each other.