In this paper, the dynamic behavior of impact test specimens are investigated by the polygon scaled boundary finite element method(PSBFEM), one of which occurs with crack propagation, others without crack propagation. The PSBFEM develops successfully with good accuracy and flexible meshing, and has become an attractive alternative for fracture analysis. No analytical asymptotic solutions and no local mesh refinement around the singularity point are required. In addition, polygon elements of arbitrary number of edges and order greatly simplify the modelling of crack and crack propagation. In the impact test, numerical models are established by only three polygon elements with plane stress assumed. Only the boundary of the polygon elements is discretized, and no local mesh refinement around the crack tip is required, which significantly improve the computational efficiency. The measured hammer load is used as dynamic load input. The dynamic stress intensity factor are directly determined by standard stress recovery techniques based on their definitions. The results correspond well with the experimental results published by Böhme and Kalthoff, and also with FDM results published by H. Stöckl and Böhme, which illustrate the accuracy and efficiency of PSBFEM.