Peroxynitrite　(ONOO-)　plays　a　pivotal　role　in　environmental　pollution　and　ecosystem　health,　necessitating　its　detection　for　assessing　ecological　impacts　and　risks.　Surface-enhanced　Raman　scattering　(SERS)　offers　high　sensitivity　but　is　often　limited　by　narrow　Raman　cross　sections　of　analytes.　Specialized　molecules　can　aid　SERS　detection,　but　are　complex　to　design　and　may　cause　nonspecific　reactions　in　biological　systems.　Therefore,　developing　new　SERS　strategies　is　crucial　for　simpler,　more　accurate　ONOO-　detection.　Herein,　the　shape　instability　of　Ag　nanomaterials　in　the　hotspots,　due　to　oxidation　and　dissolution　of　Ag　atoms　at　the　edges　and　corners,　is　investigated,　and　the　detection　of　ONOO-　is　performed　by　SERS　probes.　ONOO-　reacts　first　with　the　(111)　facet,　especially　at　the　edges　and　corners.　Consequently,　the　SERS　signal　of　the　adsorbed　probe,　Rhodamine　6G　in　hotspots　can　be　used　to　monitor　edge　and　corner　dissolution　that　positively　related　to　the　ONOO-　concentration.　As　a　result,　ONOO-　concentration　from　0.1　to　25　mu　M　was　detected,　achieving　a　coefficient　of　determination　of　R-2　=　0.9896.　The　method　exhibits　good　reproducibility　(RSD　＜　3.25%)　and　stability　(＞　7　days),　and　quantitative　detection　of　ONOO-　was　achieved　in　bovine　serum　samples.　Ag　nanocubes　exhibited　an　eightfold　stronger　response　and　higher　precision　compared　to　Ag　nanoparticles　in　ONOO-　detection.　This　simple　detection　technique　offers　a　promising　method　for　the　accurate,　quantitative　detection　of　ONOO-　in　wide　range　of　biological　systems.