The penetration performance of nanocrystalline as well as coarse-grained copper shaped charge jets was studied by experiments under the offset distance from twice to four times diameter of the shaped charges Dynamic mechanical property of copper specimen with different average grain size at high strain rates from 1700 to 6800 s-1 was tested by 14.Smm split Hopkinson pressure bar(SHPB) and the Johnson-cook constitutive parameters were obtained. Penetration process of the shaped charge jets on the targets was calculated by LS-Dyna finite element program to analyze the penetration mechanism. The results show that the penetration performance of the NC copper shaped charge jets are superior to that of the coarse-grained copper shaped charge jets by 6.7-11.7 percent due to the super plasticity of the jets.