We report the structural characterization and lattice damage induced by the energetic boron (four atoms in all) and nitrogen atoms (eight atoms in all ) with the energy of 500eV co-doped into diamond film and subsequent annealing by computer simulation based on Tersoff empirical potential. With the increasing number of implanted atoms, the affected volume is enlarged, the radius of the disrupted region reaches to 0.68nm for twelve implanting atoms. As a result of annealing, the atoms of the disrupted core can move for rather long distances up to several lattice sites. The mean bond length after annealing approaches the diamond bond length, as obtained from the pair distribution function. Since it is rich in vacancies on the near surface layer, after annealing the interstitial-vacancy recombination could take place, leading to the redistribution of the stress. Annealing at 800℃ is adequate for the recovery of the implanted diamond lattice.