Microwave has been used for the fine particle formation, the monodisperse distribution and the surface modification in the field of hydrothermal synthesis and emulsion polymerization. However, nanoparticle behavior such as aggregation and dispersion under microwave irradiation has not been clear. In this study, effect of the power and the irradiation time on the particle movement was dynamically analyzed using microwave reactor equipped with dynamic light scattering. Microwave will affect on surface charge of particle, which is related with electric double layer.