In this work, a novel biosensor was fabricated with nanocrystalline dysprosium oxide (Dy2O3) - graphene oxide (GO) as the carrier to immobilize hemoglobin (Hb) for the detection of hydrogen peroxide (H2O2). Dy2O3 and GO were firstly prepared via hydrothermal method and the traditional Hummers method respectively. The obtained Dy2O3 was characterized by field emission scanning electron microscopy (SEM) and X-ray diffraction (XRD). The GO, Dy2O3 and Hb composites were modified on the surface of the bare glassy carbon electrode (GCE) to construct the biosensor. The whole fabrication process and the electrochemical properties of the fabricated biosensor were fully studied via electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). By utilization of the synergistic effect between the electrical properties of Dy2O3 and the good conductivity of GO, the prepared biosensor provided a biocompatible microenvironment for Hb to perform direct electron transfer at the modified electrode, and exhibited excellent electrocatalytic reduction of H2O2. The fabricated biosensor showed a good linear relationship with H2O2 in the range of 5-300 mu M and the square of correlation coefficient R-2 = 0.984. This biosensor has the advantages of wide detection range, good stability and reproducibility, and strong anti-interference ability. Satisfied performance was obtained when applied for the detection of practical sample.