An　ultrasensitive　sandwich-type　label-free　electrochemiluminescence　(ECL)　immunosensor　based　on　sombrero　model　for　the　detection　of　neurotensin　(NT)　in　human　serum　and　urine　was　developed.　Graphene-hyaluronate-luminol　(G-HY-luminol)　composite　was　coated　on　the　surface　of　the　glassy　carbon　electrode　to　build　the　ECL　immunosensor,　which　gave　in-situ　ECL　signals　by　luminol.　A　secondary　NT　unlabelled　antibody　was　used　to　form　the　final　sandwich　immunocomplex　as　a　sombrero　model,　facilitating　reduction　of　the　ECL　intensity　to　improve　the　sensitivity　of　detection　significantly.　Results　showed　that　the　inhibition　of　ECL　intensity　increased　with　the　logarithm　of　NT　concentration　within　a　wide　linear　range　from　0.001　pg　cm(-3)　to　100　pg　cm(-3).　In　addition,　specificity,　stability,　reproducibility,　regeneration　and　application　were　satisfactory.　Therefore,　this　developed　ECL　immunosensor　has　a　potential　for　practical　detection　of　NT　and　NT-like　peptides　with　small　molecular　weight　in　the　clinical　diagnostics.　(C)　2014　Elsevier　Ltd.　All　rights　reserved.