Uniform,　spherical　Ag　nanoparticles　(NPs)　were　produced　using　nanosecond　excimer　pulsed　laser　ablation　of　a　colloid　target,　which　had　been　previously　prepared　using　silver　nitrate　reduction.　After　the　irradiation　experiment,　the　surface　condition　and　morphology　of　the　samples　were　revealed　by　transmission　electron　microscopy,　and　the　changes　in　the　NPs　characteristics　caused　by　different　laser　fluences　were　confirmed　using　optical　transmission　measurements　with　an　ultraviolet-visible-infrared　spectrophotometer.　A　considerable　narrowing　of　the　surface　plasmon　extinction　band　was　achieved　at　300-450　mJ　laser　irradiation　condition,　and　a　quantitative　concept　of　＂circularity＂　was　put　forward　to　estimate　the　degree　of　optimization.　In　addition,　the　effect　of　light-pressure　explains　the　cause　of　slight　collision　and　fusion　among　the　nanoparticles.　An　analysis　of　these　characteristics　offers　direct　evidence　of　good　dispersion　and　a　change　in　surface　shape　from　irregular　to　an　ideal　spherical　form.　A　surface-enhanced　Raman　scattering　(SERS)　experiment　was　proposed,　based　on　the　substrate　of　an　irradiated　Ag　nanoparticle,　and　this　showed　new　optimized　properties　for　SERS　detection.　It　also　involves　using　a　heat-melting　mechanism　to　effect　change,　which　assumes　a　solid-liquid-solid　phase　change　chain　and　can　be　explained　simply　by　triggering　the　photon　absorption　of　electrons　and　their　coupling　to　the　Ag　lattice,　which　is　then　terminated　by　a　heat　release　to　the　solvent.　(C)　2017　Laser　Institute　of　America.