The invention discloses a sealing groove forming tool, comprising a cutter bar, and a cutting edge fixed to the bottom end of the cutter bar. The cutting edge is of a circular cake type, and the crosssection diameter of the cutting edge is larger than the cross section diameter of the cutter bar. The method has the beneficial effects of being suitable for the numerical control die industry, one-time machining of the die seal ring inverted position, shortening the clamping time, reducing the machining time, and improving the working efficiency.