With laser and high-speed digital camera, digital dynamic photoelastic experiment system was established. On their own in the epoxy resin casting plane photoelastic model material, beam three impact dynamic photoelastic experiment was carried out. The experimental results show that it is feasible that the digital dynamic photoelastic experiment technology researches dynamic problem of propagation of stress wave. Drop hammer impact dynamic photoelastic experiments show that when beam is under to impact load, stress concentration appeared in beam fulcrum place first, then the large tensile stress appeared in the middle of two fulcrum location. This is why the crack usually occurs on midperpendicular of two fulcrum in three impact test, and extended from the lower to the upper edge along the bottom edge in three points impactstests;charpy internal stress model gradually translated to the static equilibrium state of " pull the pressure ", with further balance of the dynamic stress waves in the internal model.