This paper describes the assembly of 2 nm gold nanoparticles between micro-fabricated planar electrodes by using dielectrophoresis (DEP). The optimal conditions for effectively dieletrophoretic manipulation have been established through theoretical analysis and experimental validation. In the theoretical analysis, the effect of Brownian motion was taken into consideration, as well as the electrothermal flow and the AC electroosmosis flow. For effective manipulation of nanoparticles using DEP, proper high electric field strength is desired to give rise to dominate DEP effect, since the higher electric field strength increases the Joule heating and the lower strength reduces the DEP force. The current results indicate that the input voltage of 16Vp-p, 150 kHz leads to effective assembly of 2 nm gold nanoparticles. Our study proved that the DEP is capable of consistently assembling gold nanoparticles down to 2 nm in diameter with micro-fabricated electrodes, which was thought to be extremely difficult in the past.