The utility model discloses a waterlogging preventing structure for a running channel outlet bracket of a water retaining structure. The waterlogging preventing structure comprises the running channel outlet bracket, and a plurality of diversion die plates arranged on the running channel outlet bracket; each diversion die plate is composed of a supporting body, and a diversion block fixed to the supporting body; two reinforcing ribs are fixed on each supporting block; a plurality of reinforcing steel bars which pass through the two reinforcing ribs are horizontally distributed at one side of each reinforcing rib, close to each supporting body; each diversion die plate is of a prefabricated concrete structure; the supporting bodies are arranged in the running channel outlet bracket and are parallel to the bevel at the lower part of the bracket. According to the waterlogging preventing structure, the diversion die plates are arranged on the running channel outlet bracket concrete; after being poured, the running channel outlet bracket concrete is integrally embedded to the diversion die plate; therefore, the problem of waterlogging in the lower part of the running channel outlet bracket can be solved; the downstream surface of a dam is nice in appearance, and the safe operation of the structure at the downstream can be ensured.