An electrochemical immunosensor was studied for sensitive detection of Interleukin-6 (IL-6) based on a dual amplification mechanism resulting from Au nanoparticles (AuNP) Poly-dopamine (PDOP) as the sensor platform and multienzyme antibody functionalized AuNP-PDOP@carbon nanotubes (CNT). The stable and robust film, PDOP, was used to immoblize biomolecules not only for the construction of the sensor platform, but also for the signal labeling. Sensitivity was greatly amplified by using the special platform of AuNP-PDOP and synthesizing horseradish peroxidase (HRP)-antibody (Ab(2)) functionalized AuNP-PDOP@carbon nanotubes (CNT). A linear response range of IL-6 from 4.0 to 8.0 x 10(2) pg mL(-1) with a low detection limit of 1.0 pg mL(-1) was obtained by the amperometry determination. Measurements of IL-6 in human serum gave excellent correlations with standard ELISA assays. Moreover, the immunosensor exhibited high selectivity, good reproducibility, and stability.