The dynamic performance of an elastoplastic planar plate undergoing large overall motion was investigated. Considering geometric and material nonlinearities, and based on planar stress assumption, Mises yield condition and flow rule, dynamics variational equations for an elastoplastic planar plate were established using absolute nodal coordinate formulation and virtual work principle. In the numerical calculation, plastic strain of each time step was stored in the global array to achieve the iteration of plastic strain. Simulation of an elastoplastic planar plate with lumped mass undergoing large overall motion was carried out to investigate the influence of plasticity on dynamic performance of the system.