Spin excitations is correlated with superconductivity in high Tc superconductors. The spin excitations in La2-xSrxCuO4 superconductors become weaker in overdoped region and disappear in non superconducting La1.7Sr0.3CuO4 sample. However, for Fe-based superconductors, We find that, spin excitations still persist in BaFe1.85Ni0.15As2 and there is almost no difference of the spin excitation between BaFe1.85Ni0.15As2 and optimal doped BaFe1.9Ni0.1As2 at higher energy. These results suggest that the effect of electron-doping to iron-based parent compound may have a different response from the case in high-Tc copper oxides. To determine if magnetism in Fe-based materials is associated with superconductivity in heavily overdoped non-bulk-superconducting sample , we propose to carry out high energy INS measurements on BaFe1.82Ni0.18As2(Tc=8K) and non superconducting BaFe1.7Ni0.3As2 sample.