The invention discloses a cutter for skin at incision edges. The cutter comprises a first fixing part, a second fixing part that is slidably connected to the first fixing part, a first fixing pin, a second fixing pin and auxiliary components. The first fixing pin and the second fixing pin are used to be inserted into skin of a patient for fixing. The first fixing pin is vertically connected to thebottom of a first fixing plate, the second fixing pin is vertically connected to a second fixing plate, and the first fixing pin and the second fixing pin are respectively located on one ends of thefirst fixing plate and the second fixing plate far away from each other. The auxiliary components include a plurality of sets of limiting plates that can be in clamping connection with the upper surface of the first fixing plate. Each set of limiting plates contains two limiting plates for transitioning a gap between a first positioning plate and a second positioning plate. For each set of limiting plates, the adjacent sides of the two limiting plates are aligned with the two sides of a first guide groove respectively and arranged along the length of the first fixing plate. Each limiting platehas the same thickness as the first positioning plate. The cutter of the present invention achieves beautiful and tidy cutting effect on the skin at the incision edges for the patient.