An ultrasensitive multiplexed electrochemiluminescence immunoassay method was developed for the detection of tumor markers by combining a functionalized graphene nanosheets and gold-coated magnetic Fe3O4 nanoparticles (GMPs) labeled alpha-fetoprotein (AFP) antibody (GMP~Ab1). The functionalized graphene nanosheets (PDDA-G) with poly (diallyldimethylammonium chloride) (PDDA) were synthesized and used to combine with luminol-capped gold nanoparticles (Lu-Au NPs). The resulting PDDA-G@Lu-Au composite displayed an enhanced capability for the immobilization of horseradish peroxidase (HRP) and signal antibody (Ab2) to realize its electrochemiluminescence immunoassay. Great signal amplification was achieved since PDDA-G could adsorb large amount of reporter molecules (Lu-Au). Besides gold nanoparticles were not only used as carriers of Ab2 and HRP but also catalyzed the ECL reaction of luminol, which further amplified the ECL signal of luminol in the presence of H2O2. GMPs as supporting material, not only been performed the rapid separation and purification of signal antibody on magnetic field, but also enhanced the fixed capacity of Ab1 to improve detection range. In addition, the magnetic probes were readily immobilized on the working electrode of screen-printed carbon electrode (SPCEs) by magnets. Under the optimized conditions, the ECL method shows a linear range of alpha-fetoprotein (AFP) from 0.002 to 20 ng mL -1