The effects of electron density and electron temperature on the partial oxidation of benzene using a micro-plasma reactor have been studied here. The plasma was generated by the dielectric barrier discharge at the atmospheric pressure. The electron density and electron temperature are key parameters for the plasma reaction of benzene. By changing the combinations of discharge conditions including the applied voltage, discharge gap, and discharge frequency, the electron density and electron temperature could be controlled. Applying the higher voltage, both the electron density and electron temperature were increased. Along with increasing the discharge frequency and reducing the discharge gap at a constant input power, the electron density increased whereas the electron temperature decreased. Higher electron densities and higher electron temperatures resulted in the enhancement of the benzene conversion. In addition, the phenol selectivity did not varied greatly with the change of electron density, while it was slightly enhanced with the increase of electron temperature. The micro-plasma reactor made it possible to change the electron density and electron temperature largely, and it has a potential to control chemical reactions effectively.