The invention relates to an automatic assembly device for a smoke collecting hood. The automatic assembly device for the smoke collecting hood comprises a rack (4), and is characterized in that positioning clamps (5), nut press-fitting lower molds (6), overturning mechanisms (7), screw tightening mechanisms (8), screw feeders (8.12), nut press-fitting mechanisms (9), nut feeders (10) and touchingbuckle feeders (11) in the automatic assembly device for the smoke collecting hood are correspondingly connected with the rack; adjusting wheels (12) are arranged at the bottom of the rack; the positioning clamps are arranged on the middle portion of the rack; supports of the positioning clamps are fixed to the rack; a placing positioning frame (5.1) is arranged between the supports, and is provided with a positioning groove matched with the shape of the smoke collecting hood (1); the placing positioning frame is provided with a pressing device (5.2) which is located on the outer side of the positioning groove and is rotationally connected with the placing positioning frame; and the two sides of the placing positioning frame are provided with concentric rotating shafts which are connectedwith the overturning mechanisms. The automatic assembly device for the smoke collecting hood has the beneficial effects that pull-riveting nuts and touching buckles are automatically assembled, the pull-riveting nuts, the touching buckles and touching buckle screws are automatically supplied, and the smoke collecting hood is automatically overturned, and the automatic assembly device for the smokecollecting hood can be widely applied in the technical field of smoke exhaust ventilators.