A graphene quantum dots-gold nanoparticles-modified glassy carbon electrode was used to investigate the electrochemical behaviors of malachite green (MG). Cyclic voltammetry curves of MG at the modified electrode exhibited a pair of quasi-reversible adsorption-controlled redox peaks at 0.502 V (E (pa)) and 0.446 V (E (pc)) in a 0.05 mol L-1 H2SO4 solution. Under the optimal conditions, by using differential pulse voltammetry as the detection method, a linear relationship was obtained between the oxidation peak current and the MG concentration in the range of 4.0 x 10(-7) to 1.0 x 10(-5) mol L-1 with the detection limit as 1.0 x 10(-7) mol L-1 (signal-to-noise ratio of 3). The modified electrode was applied in the determination of MG in fish samples, and the results were satisfactory with recoveries from 96.25 to 98.00 %. Furthermore, the modified electrode showed very good reproducibility and stability.