Abstract: The interaction between space plasma and a high Alfven-Mach number perpendicular collisionless shock using a hybird simulation is numerically studied. The results show that in the upstream the magnetic field is very stable, and the distribution of the proton is nearly a Maxwell distribution. In the downstream the magnetic field eaists the irregular turbulence. The distribution of protons has a high energy tail and few protons 4ie reflected. Following some protons with high velocity, it is found that at t=40Ω_i^-1 about 40% of protons are reflectal by shock, and 7% of protons are accekerated(maximum velvcity up to 20V_A). The electric field in shock region has gureat influence on the deceleration and acceleration of protons.