To study the behavior of mesh bumper under hypervelocity impact, numerical simulation of aluminum projectile impacting on aluminum mesh has been carried out. Two kinds of cross wired aluminum mesh are considered, which are different in wire diameter and mesh size, and the simulated impact velocities range from 3km/s to 6km/s. The simulation results show that the debris produced by the impact is consist of some fragments clusters, some particles in the fragment clusters have higher velocities than the initial impact velocity, which leads to localized energy concentration. The velocity ratio (residual velocity/initial projectile velocity) increases while projectile velocity increases, same relation exist between the ratio of fragment dispersing velocity/projectile velocity and projectile velocity. It is concluded that single aluminum mesh has good ability of breaking up and dispersing projectile.