It is very important to assess failure mode of warship under explosion and shock loading. Stress triaxiality and Lode angle are all important factors to judge stress states of material. By combining the stress states of MMC failure criterion and strain, temperature of J-C failure criterion and taking stress states, strain and temperature into account, a dynamic failure criterion for ship-build metal was set up. A VUMAT material subroutine was introduced into ABAQUS and the ballistic perforation resistance of 2 mm ship-build mild steel was studied by simulation and experiments. The results showed that the new dynamic failure criterion based on stress triaxiality and Lode angle could predict the failure of ship-build metal under dynamic loading, which was more accurate than J-C criterion. The new criterion could be used to predict dimension of crevasse, failure mode and residual velocity under explosion, shock and penetration loading.