Graphene quantum dots (GQDs) offer new opportunities for the applications of electrochemical sensing because of their intrinsic peroxidase-like activity. To develop a sensitive electrochemical sensor with better stability and reproducibility, polydopamine (PDA) has been employed as an adhesive agent to integrate the GQDs and gold nanoparticles (Au NPs) tightly through a green, facile and rapid method. The synergistic effect of Au-PDA-GQD nanocomposite presented an excellent electrocatalytic activity towards the reduction of hydrogen peroxide (H2O2). Hence, the H2O2 biosensor based on Au-PDA-GQD exhibited better sensing performances, such as wide linear range (0.1-40 mu M and 40-20,000 mu M), low detection limit (5.8 nM) and fast response time (< 2 s) at low applied potential (-0.1 V). Also, it presented a wonderful stability, reproducibility (RSD = 1.01%) and anti interference. These results can be demonstrated that a novel Au-PDA-GQD is one of the most promising nanocomposites for the fabrication of non-enzymatic H2O2 biosensors.