Abstract: In order to ensure the realization of the special fluted tap, the characteristics of the outer contour of fluting wheel were studied, and an online dressing method to realize the contour of the specific grinding wheel was proposed. The diamond roller with semi-circular outline was used as wheel dresser. By recognizing the multi-arc outline curve designed by CAD, the dresser outline and the lowest point of the target outline are always in the tangent position. The grinding trajectory was interpolated. Finally, the trajectory of wheel dressing was realized, and the feasibility of this method was verified by experiments.