Surface-enhanced　Raman　spectroscopy(SERS)　has　unique　advantages　such　as　ultra-high　sensitivity,　fingerprint　information,　small　samples,　and　non-destructive　detection.　The　design　and　preparation　of　a　SERS　substrate　with　excellent　reproducibility　and　stability　are　key　factors　in　the　further　development　of　SERS　detection　technology.　Hydrogel　is　a　new　type　of　encapsulation　material;　its　cross-linked　polymer　network　has　a　three-dimensional　layered　structure　that　can　retain　a　large　amount　of　water　and　has　a　good　blocking　effect　on　impurities　and　strong　anti-interference　ability.　Hydrogel　SERS　substrate　has　many　advantages,　such　as　low　cost,　high　sensitivity,　rapid　detection,　and　high　throughput.　In　this　review,　the　research　process　of　SERS　substrate,　the　advantages　of　hydrogel　SERS　substrate,　and　the　application　of　hydrogel　SERS　substrate　in　the　field　of　food,　biology,　and　environmental　detection　are　mainly　reviewed　to　provide　a　new　reference　for　the　preparation　of　hydrogel　SERSsubstrate.　First,　for　the　SERS　substrate　research　process,　early　fixed　metal　nanoparticles(MNPs)　rigid　solid　substrate,　precious　MNPs　tend　to　oxidate　and　aggregate.　SERS　substrate　has　poor　reproducibility,　so　it　cannot　analyze　the　surface　rough　samples.　In　the　SERS　substrate　with　MNPs　modified　on　the　flexible　support　material,　MNPs　are　easy　to　separate　in　the　detection　process,　and　the　sensitivity　and　stability　of　the　SERS　substrate　are　poor.　The　hydrogel　is　combined　with　a　plasma　nanostructure　to　obtain　a　SERS　substrate　with　good　uniformity　and　stability.　Hydrogel,　as　the　protective　layer　of　MNPs,　provides　reliable　size　and　charge　selectivity　for　SERS　analysis　while　maintaining　high　permeability.Furthermore,　hydrogel　SERS　substrate　can　achieve　in　situ　detection　of　the　target　without　sample　pretreatment,　biocompatible　composite　hydrogels　can　be　directly　detected　in　vivo,　and　DNA　hydrogel　substrate　can　be　accurately　recognized,　hydrogel　modified　with　multiple　antibodies　allow　for　the　detection　of　multiple　analytes　simultaneously,　microgel　with　adjustable　mesh　size　have　a　selective　sieving　effect　on　the　target,　and　3D　nanostructured　hydrogel　provides　more　adsorption　hotspots.　The　prepared　hydrogel　SERS　particles,　chips-,　and　patches　show　great　potential　for　on-site　trace　analysis　in　food　safety,　biomedicine,　and　environmental　monitoring.　In　conclusion,　preparing　hydrogel　SERS　substrates　has　good　development　prospects　and　can　provide　new　references　for　future　analysis　and　detection　fields.