The utility model discloses an automatic material feeding system of a threading machine matched with a metal tube parts threading machine. The automatic material feeding system of the threading machine comprises a material feeding mechanism arranged on the middle of a manual operation clamping station and composed of a material feeding cylinder, a guiding seat, an overturning slide, a connecting plate, a guide rod, a clamping apparatus seat, a flexible clamping apparatus and an electromagnet and a detecting switch. The automatic material feeding system of threading machine further comprises a material transporting mechanism which is arranged on one side of the manual operation clamping station and composed of a low speed electrical machine, a chain, a material tray, and a material transferring mechanism arranged on the middle upper portion of manual operation clamping station and composed of a supporting plate, a guide column support, a guide column, a material transferring cylinder, a straight line bearing body, a spacing screw, a material inhaling cylinder, a material inhaling clamp and an electromagnet. The automatic material feeding system of the threading machine is characterized in that firstly, the material transporting mechanism is charged with transporting a pipe fitting in to a certain position, and then the pipe fitting transported by the material transferring mechanism is moved to the material feeding mechanism, and the material feeding mechanism moves the pipe fitting to the process station and to tapping thread operation. The automatic material feeding system of threading machine has the advantages of being stable and reliable in working, good in consistency, high in working efficiency and convenient to operate.