In this paper,an accurate micromagnetic model is built for CoPt-TiO₂ (6 nm)/Co-TiO₂(δ=1~4 nm) exchange coupled bit pattern media,based on the polycrystalline microstructure,to investigate the effect of the magnetic parameters such as the thickness,the anisotropy,the saturation magnetization of the soft layers on the coercivity of the bit pattern media. It is found that:the coercivity decreases from 8.2 kOe to 5.8 kOe when the thickness δ of the soft layer increases from 1 nm to 4 nm,whereas the normalized Mr remains 0.99. Meanwhile,the coercivity decreases when the anisotropy is lower,the saturation magnetization is larger in the soft layer and the angle θ is larger in the hard layer.