The invention discloses a dust sucking and dedusting device for cast iron manufacturing. The dust sucking and dedusting device comprises an adsorption hood, an air delivery pipe, a purifying barrel and a sundry collecting box; a first adsorption mesh and a second adsorption mesh are arranged in the adsorption hood, and the fineness of the second adsorption mesh is higher than that of the first adsorption mesh; a water storage tank is arranged on the purifying barrel, a driving motor is arranged at the end, far away from the air delivery pipe, of the purifying barrel, a rotating shaft is arranged in the driving motor, a first purifying fan is arranged at the end, far away from the driving motor, of the rotating shaft, a second purifying fan is arranged in the middle of the rotating shaft, and a first drainage hole and a second drainage hole are correspondingly formed in the portions, above the first purifying fan and the second purifying fan, of the bottom of the water storage tank. When the dust sucking and dedusting device is used for adsorbing sundries and dust, substances with large sizes are filtered; when the sundries and dust are cleaned away, by means of diversion of the fans and cleaning of the water body, small-size substances such as the dust and scrap iron are cleaned away, and great benefits are provided for human body health and working production.