Combined knife tool capable of processing diesel engine air valve seat and conduit hole

The utility model discloses a combined knife tool capable of processing a diesel engine inlet and exhaust valve seat and conduit hole, which comprises a roughing tool and a finishing tool, wherein the roughing tool comprises a handle, a boring cutter body fixed to the handle, and a boring cutter sheet which is arranged on the boring cutter and used for machining an inlet and exhaust valve seat, the end part of the boring cutter body is provided with a short cutter, and the cutting length of the short cutter is from 15MM to 25MM; the finishing tool comprises a handle, a boring cutter body fixed to the handle in a connecting mode, and a boring cutter sheet which is arranged on the boring cutter and used for machining an inlet and exhaust valve seat, the end part of the boring cutter body is provided with a long cutter which has the same axial lead as the boring cutter body and the cutting length of the long cutter is larger than the full length of a conduit hole. The utility model can avoid frequent correction to the position of a work piece and the cutter; besides, the utility model can increase the production efficiency and the machining quality of the inlet and exhaust valve seat and the conduit hole.