In this study, a novel competition-type electrochemiluminescent immunosensor for detecting brombuterol (Brom) was proposed by using CdSe quantum dots (QDs), poly(diallyldimethylammoniumchloride) (PDDA) protected graphene (P-GR) and gold nanoparticles (AuNPs) hybrid (CdSe QDs/P-GR/AuNPs-Ab) as label for the first time. The high sensitivity of ECL sensor was obtained via dual signal amplification by using the CdSe QDs/P-GR/AuNPs composite as label and AuNPs/coating antigen (Antigen-ovalbumin) as the substrate. A competitive immunoassay format was selected for quantifying Brom, where Brom in the sample would compete with the corresponding coating antigen for the limited QDs labeled P-GR/AuNPs-Ab. The linear range was from 0.01 to 1000 ng mL(-1) with a low detection limit of 3 pg mL(-1) (S/N = 3). This ECL immunosensor combined with the excellent advantages of CdSe QDs/P-GR and gold nanoparticles displayed high sensitivity, wide response range and long-term stability and provided a method for determining other important biomarkers. (C) 2016 The Electrochemical Society. All rights reserved.