Abstract: Gold nanoparticles show promising applications in the field of molecular biology and R&D of biological sensors. Aiming at overcoming the irreversible aggregation of nano-gold in electrolyte solutions, this work investigated the effect of DNA modification on nano-gold stability in the presence of sodium ions, through the characterization of UV, TEM and Zeta potential measurements. It was indicated that the Zeta potential of nano-gold depended on the diameter of particles. Nano-gold particles with diameter of 13 nm were stable at the Zeta potential of -44.4 mV, while irreversible aggregation of particles appeared quickly when a sodium buffer was added to the solution. UV spectra of kinetic properties for the DNA modified nano-gold particles reflected the high stability of the system with the addition of sodium ions.