A new efficient electrochemiluminescence（ECL） immunoassay strategy was developed for the determination of abrin based on the large specific surface area and excellent biocompatibility of GoldMag particles.The assay consisted of a double antibody sandwich format in which polyclonal antibody（PcAb） of abrin was immobilized on GoldMag particles as capture probe,and Ru（bpy）2+3-labeled monoclonal antiboday（McAb） for ECL probe.First,immobilized PcAb,abrin and Ru（bpy）2+3-labeled McAb formed sandwich immunocomplex via the specific immune response.Then abrin was determined by electrochemiluminescence（ECL） reaction.A logarithmic linear relationship（r=0.998 4） between ECL intensity and concentration of abrin in the range of 0.2-1 500 μg/L was obtained,and the detection limit was 0.2 μg/L.Compared with the biotin-avidin immobilization method,this new approach possesses more considerable sensitivity,wider linear range,more simplified steps and holds a great promise in the sensitive detection of target proteins in various fields such as clinical diagnosis,environmental monitoring and biodefense.