Hydrazide-modified　graphene　quantum　dots　(HM-GQDs)　obtained　by　refluxing　GQDs　with　hydrazine　hydrate　were　hybridized　with　gold　nanoparticles　(AuNPs)　through　a　redox　reaction　between　HM-GQDs　and　AuCl4-.　The　obtained　nano-hybrids　(HM-GQD-AuNPs)　possess　the　unique　electrochemiluminescence　(ECL)　properties　of　HM-GQDs　and　the　easy　self-assembly　with　some　bio-molecules　of　AuNPs,　which　have　great　potential　applications　in　bio-sensors.　HM-GQD-AuNPs　were　modified　on　a　glassy　carbon　electrode　to　develop　a　novel　ECL　immunosensor　of　carcinoembryonic　antigen　(CEA)　as　a　model　target　analyte.　Due　to　the　increment　of　electron-transfer　resistance　after　immunoreaction,　the　ECL　intensity　decreased　as　the　concentration　of　CEA　was　increased.　The　linear　response　range　was　between　0.02　and　80　ng　mL(-1),　and　the　detection　limit　was　0.01　ng　mL(-1).