The invention provides a downpipe installation structure and relates to a method for fixing a downpipe. The downpipe installation structure solves the problem that due to installation of the downpipe, a wall is damaged. The downpipe installation structure comprises a base and a downpipe clamping base. The base is an embedded part and is in a long-strip shape. The lower portion of the base is embedded in the wall in the downpipe installation direction. The clamping base comprises an installation portion and a clamping portion. The installation portion is fixed to the upper portion of the base and is perpendicular to the wall. The clamping portion is located on the upper portion of the installation portion. The clamping portion is in an annular shape and surrounds a downpipe body. According to an embedded mode of the downpipe installation structure, a wall structure is not damaged, damage to a waterproof layer of a wall heat-preservation layer is avoided, and consistency of the wall is guaranteed; the clamping portion is in a detachable mode, so that the damaged downpipe is conveniently replaced, reuse is achieved, and cost is saved; the clamping portion and the base are clamped and fastened through a bolt, the position of the clamping portion on the base can be conveniently adjusted, adaptive adjustment to different downpipes can be achieved, and the downpipe installation structure is more reasonable and user-friendly.