The invention belongs to the technical field of drilling tools in machining and relates to a chip breaking structure of a reducing position cutting edge of a stepped drill. The chip breaking structureis composed of a step reducing position cutting edge, a chip breaking cutter face, a chip breaking edge, a stop face, an edge strip, a chip discharging groove and a step back section end face. According to the chip breaking structure, traditional continuous spiral edge cutting is changed into step edge joint cutting, arc front cutter faces are changed into straight cutter faces mutually forming an angle, and a chip breaking space is formed. The front cutter faces mutually forming the angle enable cutting chips to bend and undergo torsional deformation, the stress of the cutting chips is increased, the breaking strength of the cutting chips is easier to reach, and therefore metal chip breaking and chip smashing are effectively achieved. The scratches, caused by continuous cutting chips, ofa hole wall are restrained, and cutter rotation deviation caused by twining of the cutting chips is reduced. The chip breaking structure facilitates to greatly improve the hole forming quality of thestep drill, reduces the machining cost and has good engineering application prospect.