Fixing device convenient for replacing boring cutter

The utility model discloses a fixing device convenient to replace a boring cutter, which comprises a main shaft and the boring cutter, an installation sleeve hole is arranged on the main shaft, an installation clamping hole is arranged on a connecting shaft of the boring cutter, an inner hole communicated with the installation sleeve hole is arranged on the main shaft, a clamping tongue is rotatably connected in the inner hole, and a spring is fixedly connected between the clamping tongue and the inner hole. When the connecting shaft is located in the mounting sleeve hole, one end of the clamping tongue is embedded into the mounting clamping hole, an annular groove communicated with the inner hole is formed in the main shaft, one end of the clamping tongue penetrates out of the annular groove, a rotating ring is rotationally connected to the main shaft, a protruding block is fixedly connected to the rotating ring, and the protruding block is located in the annular groove. The utility model relates to the tech