The cysteamine (CA) was bound onto surface of the pretreated glassy carbon electrode (GC) with cyclic voltammetry (CV). Gold nanoparticles were self-assembled to the electrode binding with cysteamine via strong AuS covalent bond to fabricate the nano-Au self-assembled modified electrode (nano-Au/CA/GC). The modified electrode was characterized with cyclic voltammetric and ac impedance methods. The electrochemical behavior of dopamine (DA) on the modified electrode was investigated with cyclic voltammetry and differential pulse voltammetry (DPV). A well-defined redox peaks of DA on the nano-Au/CA/GC electrode were obtained at E_pa=0.175V and E_pc=0.146V (vs. SCE), respectively. The peak current of DA is linear with the concentration of DA in the range of 1.0×10⁻⁸molL⁻¹ to 2.5×10⁻⁵molL⁻¹, with the correlation coefficient of 0.998. The detection limit is 4.0×10⁻⁹molL⁻¹ (S/N=3). The modified electrode exhibited an excellent reproducibility, sensibility and stability for determination of DA in the presence of high concentration AA, and can be applied to determinate dopamine injection, with satisfied result.