The utility model provides an inverted roof cornice waterproof joint structure. The inverted roof cornice waterproof joint structure comprises a cornice bottom plate, a painting layer, a window frame,a leveling layer, a waterproof layer, a heat preservation layer, a protection layer, a cement bonding layer, roof tiles, an end cement bedding mortar layer, an anti-corrosion wood pad and cornice tiles. A painting layer is built below the cornice bottom plate, a water dripping line is further built on the painting layer and located below the end of the cornice bottom plate, the bottom of the lower connecting beam is connected with the top of the window frame, and a leveling layer is built above the cornice bottom plate. A waterproof layer is laid on the leveling layer in an attached mode, anda heat preservation layer is laid on the waterproof layer in an attached mode. Wherein a cement bonding layer is arranged on the protective layer, roof tiles are bonded on the cement bonding layer, afull-length anti-corrosion wood pad is fixed above the end part of the protective layer, an end part cement bedding mortar layer is arranged above the anti-corrosion wood pad, and the end part cementbedding mortar layer wraps and tamps the end parts of the roof tiles; a cornice tile is arranged outside the end cement bedding layer, and the lower portion of the cornice tile is fixed to the anti-corrosion wood pad through steel nails.