An　ideal　surface-enhanced　Raman　scattering　(SERS)　substrate　should　have　high　sensitivity,　long-term　stability,　excellent　repeatability,　and　strong　anti-interference.　In　the　present　work,　single-layer　carbon-based　dot　(CD)-capped　Ag　nanoparticle　aggregates　(a-AgNPs/CDs)　with　high　SERS　activity　are　synthesized　and　hybridized　with　a　hydrogel　to　prepare　novel　hydrogel　SERS　chips.　Benefiting　from　the　unique　properties　of　a-AgNPs/CDs　and　the　hydrogel,　the　constructed　hydrogel　SERS　chips　show　excellent　performances.　Taking　crystal　violet　detection　as　an　example,　the　hydrogel　SERS　chips　show　a　detection　limit　of　around　1　×　10-16　mol/L　(high　sensitivity),　maintain　above　96.40%　of　SERS　activity　even　after　14　weeks　of　storage　(long-term　stability),　and　display　point-to-point　relative　standard　deviation　(RSD)　in　one　chip　as　low　as　1.43%　(outstanding　repeatability)　and　RSD　in　different　chips　as　low　as　2.75%　(excellent　reproducibility).　Furthermore,　the　self-extraction　effect　of　the　hydrogel　enables　the　flexible　hydrogel　SERS　chips　to　be　used　for　analyzing　various　real　samples　including　soybean　milk,　juices,　and　fruits　without　any　complex　pretreatment.　For　instance,　the　hydrogel　SERS　chips　are　able　to　detect　trace　thiram　and　2-(4-thiazolyl)benzimidazole　with　the　detection　limits　of　1　and　5　ppb　in　liquid　samples,　respectively,　and　of　1　and　2.5　ng/cm2　on　the　peel　of　fruits,　respectively.　The　self-extraction　functional　flexible　SERS　chips　offer　a　reliable　and　convenient　platform　for　the　quick　detection　and　on-site　monitoring　of　chemical　contaminants.