Abstract: A ventilating hood and a helmet with the ventilating hood consist of a helmet, a ventilating hood fixed on the top of the helmet and a warning light. The helmet has an air vent and an air exit on its top. The air guiding hood has an air entrance and an air exit respectively opened at its front side and rear side, and an accommodating chamber formed in its bottom to guide air current, able to keep a user free from closeness and discomfort. Also, the warning light installed behind the air-guiding hood can not only attract more attention, but also keep the helmet remained intact without damaging its structure.