As　one　of　paralytic　shellfish　toxins,　the　saxitoxin　(STX)　in　the　aqueous　environment　can　be　accumulated　by　most　shellfish,　and　thus　harms　human　health　through　the　food　chain.　Therefore,　it　is　crucial　to　determine　trace　STX　in　seafood　samples　in　order　to　ensure　the　safety　of　seafood　consumption.　In　this　study,　we　developed　a　novel　indirect　method　for　ultrasensitively　determining　trace　STX　in　seafood　by　using　CE-ICP-MS　together　with　Eu3+　chelate　labeling.　We　demonstrated　that　diethylenetriamine-N,N,N＇,N＇＇,　N＇＇-pentaacetic　acid　(DTPA)　can　couple　with　STX　and　simultaneously　chelate　with　Eu3+　to　realize　metallic　labeling　of　STX,　and　thus　realize　the　ultrasensitive　quantification　of　trace　STX　with　CEICP-MS.　The　proposed　method　has　strong　antiinterference　ability,　good　stability,　and　extremely　high　sensitivity.　It　could　be　used　to　determine　trace　STX　in　seafood　samples　with　an　extremely　low　detection　limit　of　0.38　fmol　(3.8x10(-9)　M,　100　nL　sample　injection)　and　a　relative　standard　deviation　(RSD,　n　=　5)　＜　7%.　The　success　of　this　study　provides　an　alternative　to　precise　quantification　of　ultra-trace　STX　in　seafood　samples,　and　further　expands　the　application　of　ICP-MS.