The utility model relates to a stay cable lower guide pipe rain cover early warning protection structure. As a stay cable adopts a sealed lower guide pipe rain cover, the detection difficulty of the inside of the lower guide pipe is very great. The stay cable lower guide pipe rain cover early warning protection structure comprises a stay cable lower guide pipe rain cover arranged on the stay cable, wherein a glass fiber reinforced plastic protection cover annularly sheaths and is fixed on the stay cable lower guide pipe rain cover arranged on the stay cable, the upper part of the glass fiber reinforced plastic protection cover is in a cylinder shape, the inner diameter of the glass fiber reinforced plastic protection cover is identical to the outer diameter of the stay cable, the lower part of the glass fiber reinforced plastic protection cover is in a round trumpet shape, the inner diameter of the glass fiber reinforced plastic protection cover is gradually increased from top to bottom, and the gap between the top edge of the stay cable lower guide pipe rain cover and the round trumpet-shaped part of the lower part of the glass fiber reinforced plastic protection cover is circumferentially and uniformly provided with a plurality of cube rubber pad blocks. The stay cable lower guide pipe rain cover early warning protection structure has the advantages that a transparent protection cover is added outside the original waterproof cover, the double-layer protection is formed for a stay cable lower guide pipe, the inside condition of the early warning protection structure can be clearly observed, and the waterproof performance of the early warning protection structure can be checked without adopting non-destructive inspection equipment or opening the protection cover.