Abstract: A microstructure model of ordered FePt:Au nanogranular films was constructed. The magnetization reversal mechanism of FePt:Au granular films with different percentages of non-magnetic Au were investigated by micro-magnetic simulation. The results show that the reversal mechanism significantly depends on the percentage of Au. As the interaction coefficient of proportionalityβ, which reflects the percentage of Au, is greater than 0.4, the reversal model is coherent and the coercive force increases slightly with reducing ft. But forβ〈 0.3, the coercive force increases quickly with reducing fl, and the consistency of magnetization reversal is weakened. It is estimated that as the space length between the FePt granulars varies from 3 nm to 4 nm, the interaction of granular exchange is near to zero and the magnetization reversal is incoherent.