A lightweight concrete exterior wallboard is characterized in that the lightweight concrete exterior wallboard comprises 34.5-43 wt% of coarse ceramsite (phi 0.5-1.0 cm), 6.9-17.2 wt% of medium ceramsite (phi 0.3-0.5 cm), 13.8-25.8 wt% of ceramsite powder (phi 0.3 cm or less), 13-21 wt% of cement, 0.13-0.92 wt% of a waterproof agent, 0.098-0.69 wt% of a water reducer and 0.065-1.15 wt% of an antifreeze agent. The lightweight concrete exterior wallboard solves the problems of high water absorption rate, easy cracking and shedding of pasted tile stones, poor integral structural strength, poor impact resistance and poor bending load resistance of aerated cement bricks, furnace slag and fly ash bricks, and fly ash, broken stone and cement bricks which are widely used in non-bearing exterior walls in existing buildings, and is suitable for being used in buildings.