The utility model discloses a nut of visual temperature variation, include: nut body and luminous body, nut body appearance the same with ordinary nut, the terminal surface is opened about the nut body has round ring groove, the luminous body make for heat sensitive material, the luminous body through the injection molding machine mould plastics inject the recess of nut body in, and luminous body upper surface and nut body be at the coplanar, the heat sensitive material that selects of luminous body manufacturing be reversible heat sensitive material, its colour with temperature changes, the nut body on the circle ring groove the cross -section shape of falling T presents, the nut body on circle ring groove bottom surface be the cockscomb structure, the nut body adopt wolfram steel to make. The utility model has the advantages of low in cost, excellent in use effect, long service life.