The influence of void configuration on void coalescence in single crystal copper under shock loading along ［100］ direction has been investigated with molecular dynamics （MD） simulation. The results reveal that the voids collapse and grow by means of emission of shear dislocation loops. In the tension stage, the voids first grow independently, then the plastic zone around the voids begin to interact and overlap, leading to the void coalescence. The pattern of void coalescence observed in our simulations coincides with the microscopic experimental results. We calculated for four different configurations, characterized by the angle （θ） formed by shock direction and the line connecting the two centers of voids, and found that among the four configurations，the coalescence of the voids prefers to occur where θ is 60°. Based on the resolved shear stress model around the void, we can clearly explain the simulation results.