The resistance of metallic sandwich plates to blast loading is studied in this work. Two typical cores, i.e. trapezoidal plate core and metallic foam core are considered in the analysis. The normal and longitudinal compressive stresses of the trapezoidal plate core are analytically and numerically obtained. Large deflection and resistance of metallic sandwich plates to blast loading are numerically analyzed. The results are compared with that of monolithic solid plates made of the same material and having equivalent weight. It is shown that the well-designed sandwich plates possess higher resistance to blast loading than monolithic solid plates.