A computer simulation study has been performed to investigate the intrinsic defects in MgAl_2O_4 by using empirical potential parameters.Through calculating the crystal structure,lattice energy,intrinsic defects formation energies and the defects cluster binding energies,it is found that the intrinsic defects in MgAl_2O_4 should be magnesium vacancy,oxygen vacancy and a little Al~+_(Mg) defect,and the effective electricity compensate mechanism is pair and cluster.