The invention discloses an automatic indexing circular milling flute fixture, which comprises an upper guide rail, a lower guide rail, a motor, a rotating cam, a connecting rod, a fixed support plate, a rotation shaft, a body, a ratchet wheel, an indexing gear, a clamping device, a brake device, a rotating device and a fixed plate, wherein the rotating cam is arranged on a spindle of the motor; one end of the connecting rod is moveably connected to the rotating cam while the other end of the connecting rod is connected to the body; the braking device and the rotating device are arranged on the body; the fixed plate is arranged on the lower guide rail; the brake device and the rotating device are connected to the fixed plate; the brake device is matched with the indexing gear; and the rotating device is matched with the ratchet wheel. The automatic indexing circular milling flute fixture has the advantages of reasonable design, high production efficiency, low cost, high quality of processed products, and the like.