The invention discloses a large H-shaped steel turnover device and a use method thereof. The large H-shaped steel turnover device comprises a plurality of mutually matched circular supporting seats, each circular supporting seat comprises a circular supporting frame or two semicircular supporting frames, a rectangular hole is arranged in the middle of one circular supporting frame, the two semicircular supporting frames are folded and then fixedly locked to form a completely circular structure, foldable rectangular grooves are arranged in the middles of folding surfaces of the semicircular supporting frames respectively, the two rectangular grooves are folded to form a rectangular hole, and limit devices for clamping H-shaped steel to be turned over are arranged on the inner walls of the upper end and the lower end of the rectangular hole respectively. The large H-shaped steel turnover device is reasonable in structural design, the large H-shaped steel can be easily turned over without the aid of a travelling crane by one to two persons when the large H-shaped steel is continuously welded in a flange thickening manner, the large H-shaped steel turnover device is convenient to operate and high in efficiency, the method is simple, and time is saved.