Ag–Ag₂O composite structure, with fine tunability of localized surface plasmon resonance (LSPR), was fabricated by using Nd:YAG fiber pulsed laser ablation at ambient conditions. In this structure, tunable LSPR of Ag nanoparticles (NPs) with the wavelength from 384 nm to 486 nm was realized by varying the laser power to regulate both the oxidation degree and the spacing of Ag NPs. Moreover, Surface enhanced Raman scattering (SERS) was also observed due to the composite structure, which was demonstrated excellent stability and SERS sensitivity with the detectable concentration of Rhodamine B as low as 10？11 mol/L. The SERS substrates fabricated by laser ablation also exhibited favorable reproducibility and uniformity. The simulation results of finite difference time domain (FDTD) regarding the electric field distribution of all samples are in good agreement with those of above results.