Abstract: An EMI preventive AC line filter includes rack having a rectangular top open chamber and two substantially U-shaped support arms at two opposite ends of the top open chamber, a cylindrical winding holder formed of two symmetrical halves and mounted in the top open chamber of the rack, the winding holder having an axially extended cylindrical coupling groove at the center, and an iron core coupled to the winding holder and secured to the rack to hold the winding holder in place, the iron core having a U-shaped peripheral wall forced into engagement with the U-shaped support arms of the rack, and a cylindrical shaft connected between two parallel side wall portions of the U-shaped peripheral wall and received in the axially extended cylindrical coupling groove in the winding holder.