Nanometer gold particles have received much attention as potentially useful materials showing novel electronic, optical, magnetic, and thermal properties derived from the quantum sized effect. Both size and shape of gold nanoparticles are evidence that affect properties of optical and electronic. Recently, thermal factor has been proven to have effects on the size distribution and uniformity of colloid-particles. The high thermal-treatment-rate and short sintering-time make microwave irradiation a promising method for obtaining nanostructured materials. To date, the preparation of nanometer gold particles by microwave irradiation has not been report yet, especially the discussion of the thermal effect on particle growth. In this work, the synthesis of gold nanoparticles by microwave irradiation with precise temperature controlled is studied.