Surface-enhanced Raman scattering (SERS), which combines nanostructured materials with Raman spectroscopy, solves the problem of low sensitivity of traditional Raman scattering technique and provides a new technical means for trace detection. High SERS active substrate is the key to the application of Raman spectroscopy for trace detection. The island nanoporous gold SERS substrate was prepared by dealloying precursor alloy films which sputtered on silicon wafer, and the obtained substrate posses much smaller ratio between pore size and gold ligament size compared with traditional nanoporous gold, resulting in much stronger local electromagnetic field due to improved coupling effect between gold ligaments. The detection limit of the substrate can reach about 10^-10 mol·L^-1, and the relative intensity of SERS spectrum has a good linear relationship with the concentration, and the dynamic range can reach 3 orders of magnitude. Meanwhile, with uniform structure the substrate exhibits stable performance, and the preparation process shows good repeatability.