The main objective of this study was to explore the dynamic response and damage pattern of a clamped square steel plate under the synergy effect of blast and fragments loading. A numerical-simulation tool was used to further study the combined blast and fragments loading effects on a clamped square steel plate. Through finite element program ANSYS/LSDYNA, simulations of the response behavior and damage pattern of the plate subjected to the combined blast and fragments loading were conducted. Large punched hole caused by the dense fragment cluster will form in the intensively impacted area under proper launch distance. As launch distance increases, large deformation is the main failure modes of the plate, combined with numbers of perforation holes but no large punched hole.