The extinction properties of the Au nanoparticle arrays with different spacings in different media are simulated by Discrete Dipole Approximation(DDA) method.The simulation result demonstrates that the extinction wavelength and intensity increase with the decreasing spacing,but the refractive index(RI) sensitivity remains constant while the spacing is large enough.And the experimental measurements of the Au nanosphere arrays assembled on the glass substrate also obtain the same RI sensitivity with different density distributions of nanoparticles in the arrays.Therefore,the local uneven distribution of the nanoparticle arrays would not change the RI sensitivity as the spacing between nanoparticles is large enough,and the red-shift of the extinction wavelength and the RI change of the surrounding medium are related directly.