Cutting blade structure of tapping machine

The utility model relates to a cutting blade structure of a tapping machine. A plurality of blade undertaking portions are evenly distributed on the periphery of the tapping machine, a cutting blade is correspondingly and fixedly arranged on each blade undertaking portion, a cutting surface is arranged at the front end of the cutting blade, a scrap guiding surface is arranged on one side which is close to the cutting surface, a turning point is formed on a contacting position of the cutting surface and the scrap guiding surface, wherein the scrap guiding surface is provided with an inwardly concave arc-shaped section, and the radian of the inwardly concave arc-shaped section can be made into different guiding radians according to material characteristics of workpieces. Therefore, scraps can be effectively guided to be drained smoothly, and cracking of the cutting blade and external threads of a processing part is prevented.