Molecular dynamic simulations, utilizing the Tersoff many-body potential, are used to investigate the microscopic processes of a single boron atom with an energy of 500 eV implanted into the diamond (001) 2×1 reconstructed surface. By calculating the variation of the mean coordination number with time，the lifetime of a thermal spike created by B bombardment is about 0.18ps. Formation of the split-interstitial composed of projectile and lattice atom(B—C) is observed. The total potential energy of the system decreases about 0.56 eV with a stable B split-interstitial existing in diamond. Lattice relaxations in the diamond (001) 2×1 reconstructed surface or near surface of the simulated have been discussed, and the results show that the outermost layer atoms tend to move inward and other atoms move outward, while the interplanar distance between the outermost layer and the second layer has been shortened by 15%,compared with it s starting interplanar distance. Stress distribution in the calculated diamond c onfiguration is inhomogeneous. After boron implanted into diamond with an energy of 500 eV, there is an excess of compressively stressed atoms in the lattice, w hich induces the total stress being compressive.