Joint cutting die for manufacturing of dividing joint during plastering of external wall

The invention discloses a joint cutting die for manufacturing of a dividing joint during plastering of an external wall. The joint cutting die comprises a joint-cutting positioning strip, a joint cutter and a chamfered bar, wherein the joint-cutting positioning strip is rectangular and made of stainless steel, the thickness of the joint-cutting positioning strip can guarantee the rigidity and non-deformation performance, a rectangular cavity as wide as the dividing joint is hollowed out in the middle of the joint-cutting positioning strip, and the width of the joint-cutting positioning strip is equal to the sum of the width of the dividing joint plus 50-60 mm; the joint cutter is formed by welding a large square stainless steel tube, a small square stainless steel tube and a round stainless steel tube; the chamfered bar is made of a PP-R polystyrene tube, the diameter of the chamfered bar is determined according to the width of the dividing joint, the chamfered bar is 250-300 mm long, one end of the chamfered