Molecular dynamics simulations were used to study the plastic behavior of copper monocrystal under shock loading and unloading. We obtained the Hugoniot relation for both ［001］ and ［111］ orientations and the melting pressure, which turns out to be in agreement with experiment. The results showed that higher initial temperature increases the possibility for the dislocation loop generate and expansion. The release behavior after the shock wave reaching the back of the sample was also analyzed. We found that the release behavior was quasi-elastic and most of the stacking-fault networks disappear behind the release wave along ［001］ orientation while few stacking faults disappear along ［111］ orientation.