Development　of　a　facile　and　cost-effective　surface-enhanced　Raman　scattering　(SERS)　sensor　with　high　sensitivity　for　the　on-site　rapid　detection　of　trace　molecules　is　a　compelling　need.　Here　we　report　how　a　capillary-based　three-dimensional　network　porous　silica　material　decorated　with　gold　nanoparticles　(3D-PSM@AuNPs)　serves　as　an　ideal　platform　for　the　rapid　static　liquid-phase　detection　of　trace　molecules.　The　SERS　sensor　is　prepared　by　an　in　situ　polymerization　method　to　form　a　3D　continuous　interconnected　porous　network　in　an　ultraviolet　transparent　quartz　capillary　with　a　facile　fabrication　process.　The　unique　porous　network　of　the　silica,　which　could　provide　a　high　specific　surface　area　in　a　focus　volume,　endows　the　resultant　material　with　a　high　density　of　SERS　enhancement　sites　and　a　＇hot-spot＇,　which　has　precisely　guaranteed　the　detection　sensitivity.　More　importantly,　the　unique　structure　of　the　capillary　could　also　present　an　aid　to　reduce　the　energy　loss　of　the　laser　via　multiple　reflections　and　thus　effectively　improve　the　utilization　rate　of　the　laser　beam.　Using　4-mercaptopyridine　(4-MPY)　in　aqueous　solution　as　a　model　molecule,　the　porous　silica　material　exhibits　a　high　detection　sensitivity　(10–11　M),　excellent　stability,　and　repeatability.　Moreover,　the　obtained　3D-PSM@AuNP　sensor　is　applied　for　the　analysis　of　phosmet　residues　on　orange　peel　and　vegetables.　The　results　demonstrate　that　this　3D-PSM@AuNP　sensor　can　successfully　realize　Raman　reporter-free　and　rapid　on-site　detection　of　trace　molecules　in　liquids,　which　provides　a　promising　platform　in　various　fields　of　micro-volume　liquid　sample　analysis,　especially　in　liquid　biopsy　analysis.　©　2022　American　Chemical　Society