Construction method of pitched roof and erection structure of form board

The invention relates to a construction method of a pitched roof and an erection structure of a form board. The erection structure of the form board comprises an overhanging steel beam, an unloading steel wire rope, a protective scaffold, a form board support and a pitched roof form board, wherein the overhanging steel beam is arranged at the periphery edge of a floor slab of a lower second layer of the pitched roof, convexly extends out of the floor slab of the lower second layer of the pitched roof and is fixedly connected with the floor slab of the lower second layer of the pitched roof; the unloading steel wire rope is pulled between an edge of a floor slab of a lower first layer of the pitched roof and the outer periphery of the overhanging steel beam; the protective scaffold is erected on the overhanging steel beam and is arranged on the outer periphery of the overhanging steel beam; the form board support is erected on the overhanging steel beam and the floor slab of the lower first layer of the pitched roof; and the pitched roof form board is arranged on the form board support. The convex overhanging steel beam is arranged at the position of the floor slab of the lower second layer, the protective scaffold and the form board support can be erected on the overhanging steel beam, the time and the labor are saved during construction of the pitched roof, safety of construction is ensured, and construction difficulty of the form board of the overhanging pitched roof is reduced well.