The utility model discloses an installing structure of a prefabricated forming gypsum board. The installing structure comprises the prefabricated forming gypsum board (2) and a T-bar system, wherein the prefabricated forming gypsum board (2) is provided with at least one corner, the T-bar system is fixed on a building structure, and the prefabricated forming gypsum board (2) is connected with the T-bar system. An assembling type construction technique is adopted in the installing structure of the prefabricated forming gypsum board, an external corner effect of overlapped-order scraping is achieved, construction is cost-saving and labor-saving, and a construction mode of finished products of circular ceilings, arc-shaped ceilings and special-shaped ceilings can be achieved.