Abstract: Graphene oxide (GO)-AuNPs@Ru(bpy)₃²⁺ nanocomposite was prepared by electrostatic interaction of AuNPs and Ru(bpy)₃²⁺. GO-AuNPs@Ru(bpy)₃²⁺ further reacted with GO to form GO-AuNPs@Ru(bpy)₃²⁺ which was used as the substrate material for ECL detection. Streptavidin (SA) can strongly bind with 4 biotin molecules to form SA-biotin. The enhanced electrochemiluminescence (ECL) signal was obtained by the combination of SA-biotin with the recognition element such as aptamer. An ECL aptasensor for sensitive detection of carcinoembryonic antigen (CEA) was fabricated based on GO-AuNPs@Ru(bpy)₃²⁺ and SA-biotin. This aptasensor exhibits a linear relation in the range of 1.0 fg/L to 10.0 pg/L with the detection limit of 0.40 fg/L. The proposed method was successfully applied in determination of human serum samples with recoveries of 80.0%~108.0% and RSDs less than 8.3%.