The invention discloses a self-cleaning special-shaped double-layer structured wall pipe and an installation method thereof. The structured wall pipe comprises an outer layer pipe and an inner layer pipe of which the section contours are both in a melon seed shape, and a supporting layer is arranged between the outer layer pipe and the inner layer pipe; and the large ends of the section contours of the outer layer pipe and the inner layer pipe are arc-shaped tops, the small ends of the section contours of the outer layer pipe and the inner layer pipe are arc-shaped bottoms, the side surfaces of the outer layer pipe and the inner layer pipe are side arc parts which are in tangent connection with the arc-shaped tops and the arc-shaped bottoms, and the side arc parts are tangent to the lowerhalf portions of circles where the arc-shaped tops and the arc-shaped bottoms are located. The sewage draining pipe has the characteristics of being high in sewage draining capacity, low in blockage probability and capable of achieving self cleaning and moreover, has the characteristics of being low in weight, small in material using quantity and high in structure strength.