The invention relates to an air conditioner external unit cover which comprises a shading plate, a decoration plate and a bracket, wherein the bracket consists of two C-shaped frames; each C-shaped frame is divided into three structural ends; socket slots are formed in the upper ends of the C-shaped frames, sliding chutes are formed in the middle ends of the C-shaped frames, and fixing pins with screw holes are arranged at the lower ends of the C-shaped frames; the shading plate and the decoration plate are respectively independent; during the use, the shading plate and the decoration plate are respectively inserted into the socket slots and the sliding chutes; the fixing pins are fixed on fixing pins of an air conditioner external unit base through screws. The air conditioner external unit cover has the benefits that the problem that the common air conditioner external unit cover is difficult to replace due to damage is solved, and the shading plate or the decoration plate can be randomly and conveniently replaced according to the style of an external wall of a building or the favor of a user.