The invention discloses a large-span suspended ceiling reinforcing and mounting device which comprises bearing keels, a plurality of supporting keels, a plurality of connecting pieces and a plurality of connecting pieces, the bearing keels are arranged at intervals in the width direction of a to-be-suspended ceiling area to form a bearing
keel layer, and first hanging rods are arranged on the bearing keels; the framework layer comprises a plurality of main keels arranged at intervals in the length direction of the bearing keels and connected with the bearing keels and a plurality of auxiliary keels connected with the main keels; the two vertical base plates are located at the two ends of the bearing
keel layer correspondingly and extend in the width direction of the bearing
keel, and meanwhile the two sides of each vertical base plate abut against the corresponding side wall of the to-be-suspended ceiling area and the end of the bearing keel layer correspondingly; at least part of the second suspenders are arranged corresponding to the bearing keels, and inclined rods connected with the bearing keels are further arranged on the second suspenders; the upper portion of the arc-shaped supporting plate abuts against the main keel located on the side and is connected with the main keel and the bearing keel at the same time, and the lower portion of the arc-shaped supporting plate is connected with the vertical base plate. The bearing requirement of the large-span suspended ceiling can be met, and the durability of the large-span suspended ceiling is improved.