The utility model discloses a down-draft resisting device used for a gas water heater. The key point of the design is characterized in that the down-draft resisting device comprises a pipe body; a rotatable wind retaining sheet which can close or open the passage of a pipe is arranged in the pipe body by a rotary shaft; the pipe body is also internally provided with an internal ring that positions the rotation angle of the wind retaining sheet; and a sealing ring is arranged between the internal wall of the pipe body and the internal ring. The utility model aims at providing the down-draft resisting device, which is used for the gas water heater, can effectively prevent down-draft, can avoid the gas water heater from accumulating water and icing in cold weather, has simple structure and is convenient for use.