The invention belongs to the technical field of steel production, and relates to a method for producing a hot-radical spangle-free galvanized plate for pre-engineered metal buildings based on a hot rolled strip production line and an acid plating continuous production line, in particular to a 450-MPa-grade hot-radical spangle-free high-strength galvanized plate for the pre-engineered metal buildings and a production method of the 450-MPa-grade hot-radical spangle-free high-strength galvanized plate. According to the production method, galvanizing raw materials with the thickness being 1.0-2.0mm are provided by the full headless hot rolled strip production line, then a hot-galvanized coiled plate is produced through straightening, phosphorus breaking, acid pickling, flattening, heating, galvanizing, finishing, passivating, tensile straightening and rolling by the continuous acid pickling galvanizing production line, that is, through processes such as flattening before galvanizing (a roughening process), electromagnetic induction heating (the in-furnace time is 20-50 s), finishing after galvanizing, dual tensile straightening, and roller coating surface treatment, thin-specification450-MPa-grade hot-radical spangle-free high-strength steel for cars can be produced, and the effect that cold rolling is replaced with hot rolling is achieved.