The utility model discloses a boring cutter body for a large-aperture thick-wall seamless steel tube. The boring cutter body comprises a boring cutter body, a boring cutter body support arm and a boring cutter clamp, wherein the boring cutter body is divided into a connecting section and a mounting section, the connecting section is provided with a cutter bar connecting counter bore, the side wallof the mounting section is provided with a mounting plane, the mounting plane is provided with a support arm connecting threaded hole, and the end part of the mounting section is provided with a cutter holder positioning threaded hole and a cutter holder fixing threaded hole; the top of the boring cutter body supporting arm is provided with an end and supporting arm fixing through holes, the supporting arm fixing through holes are located in the two sides of the end, and the boring cutter body supporting arm is fixed to the boring cutter body. The boring cutter clamp is provided with a cutterclamp adjusting through hole and a cutter clamp fixing through hole, the cutter clamp fixing through hole is located in the outer side of the cutter clamp adjusting through hole, the boring cutter clamp is fixed to the end of the boring cutter body, and the boring cutter head is installed in the cutter head connecting threaded hole. By adopting the split type cutter body, the boring cutter clamp,the boring cutter body and the boring cutter body support arm are separated, so that the auxiliary time for replacing the boring cutter body can be shortened, and the processing capacity and the processing efficiency of a product are improved.