The invention discloses a fabricated self-heat-preservation metal decorative outer wall board which comprises a metal shell and a wall body. The metal shell forms the outer surface of the outer wall board, and the wall body is poured into the metal shell; after being hardened, the metal shell and the wall body are combined into the overall outer wall board; the metal shell is of a groove-shaped half-surrounded structure, and the groove opening edge of the metal shell is inwards folded by 90 degrees; the length of the metal shell is equal to that of the wall body, the width of the side face is 30-80 mm, and the metal shell is made of 0.8-2.0 mm metal sheets with decorative and water-proof effects; and the side where the metal shell is located serves as the outer side of the wall body, and the wall body sequentially comprises 30-100 mm thick light high-specific-strength high-porosity concrete, a 0-50 mm heat-preservation layer and 100-160 mm thick light high-specific-strength low-porosity concrete from outside to inside. According to the outer wall board, the problems that in a current building wall board, the self-weight is large, the water-proof effect is poor, the heat-preservation effect is poor, and assemblage is difficult to achieve are solved, and the functions of decoration, heat preservation, water resistance and the like are integrated, so that adoption of assembly construction of building industrialization is facilitated.