The point defect properties of L12 Ni3Al are determined by MD with a simple modified analytic EAM model with the basic physical properties of pure constituents Ni and Al. On the basis of the calculated lattice constants, the formation energies of vacancy and antisite are calculated and the defect types are also discussed. The energies of alloying element Re replacing Ni site and Al site in Ni3Al are estimated. The occupational site of Re is found in Al site. The present calculations are in agreement with the experimental value and the theoretical results obtained from other authors.