The invention discloses a machining process for a scalpel. The machining process comprises the following steps that 1, a round slotting tool is clamped by a collet to form a deformed round slotting tool, so that the diameter of the round slotting tool is decreased; 2, the deformed round slotting tool body in the step 1 is put into a through hole of an outer aluminum pipe sleeve; and 3, an ejector rod is put into the through hole of the outer aluminum pipe sleeve and is pushed to drive the deformed round slotting tool to move. The cutting edge angle between the outer surface of each first elastic tool blade and a corresponding inclined surface as well as between the outer surface of each second elastic tool blade and a corresponding inclined surface is 60-75 degrees. The tail ends of a plurality of first line through grooves and the tail ends of a plurality of second line through grooves are provided with bottom cutting edges. According to the machining process for the scalpel, certain elastic force can make contact with the inner wall of an aluminum pipe at any time and does not damage the inner wall, and small convex points on the inner wall can be removed to the greatest extent.