Abstract: By introducing the membrane force factors，the motion equations of rectangular plates in the case of small deflection are modified to fit in the case of large deflection，and the corresponding dynamic plastic response is analyzed. Meanwhile，the motion differential equations of fully-clamped rectangular plates subjected to blast loads are derived，with the loads being rectangular pulses. Therefore，the formulas of maximum permanent deformation of rectangular plates can be solved. In addition，this paper investigates the problem of yield stress increasing under high strain rate by employing an assumed selection method for the strain rate effect coefficient. Finally，the proposed motion patterns are verified with a finite element method，where the existing experimental samples and the new finite element models are both calculated using the described theoretical method. The results are then compared with those obtained from previous experiments as well as finite element simulations，and good agreement between the two can be clearly observed.