In foregoing study, a new phenomenon of the local dent of upper face sheet occurs in the simulation of dynamic response of sandwich plate subjected to blast loading. The reason and the effect of local dent on energy absorption are not ascertained. In this paper, two kind of square honeycomb plate with the cell wall thickness of 1mm and 0.5mm and with the same mass are modeled. And the dynamic response of both plates subjected to blast loading is simulated using LS-DYNA. For the thicker cell wall (1mm), the local dent is obvious while for the thinner cell wall (0.5mm), the local dent is not obvious and can be ignored. In addition, curves of the ratio of the maximum deflection of lower face sheet of sandwich plate to monolithic solid plate vs the mass of TNT charge as well as the ratio of internal energy are obtained. The results indicate that the local dent has the contribution to the energy absorption of sandwich plate especially in early time and the sandwich plate with the core of thinner cell wall has more effective capacity in blast-resistance than that with the core of thicker cell wall.