The utility model relates to a toilet especially relates to the indoor pressure adjustment assembly in toilet. An invariable device of indoor pressure differential in toilet, the toilet is equipped with the exhaust pipe of supply -air outlet, return air inlet and inside plant, the exhaust pipe of equipment is divideing into indoor pipe and outdoor pipe, outdoor tub of one end run -on fan group, and the other end penetrates indoorly, and its pipe diameter is greater than the pipe diameter of indoor pipe, and indoor pipe end portion inserts outdoor intraductally. Through the utility model discloses can reach manufacturing equipment open or the block state under, room pressure differential is unchangeable.