Based on the Vaughan model, a simplified two-dimensional multipactor model of the circulator junction is established in this paper. It consists of two parallel metal plates and a dielectric plate that is vertical to the metal plate. A radio frequency electric field is applied between the two metal plates, and an electrostatic field exists on the dielectric surface. The trajectory of the electron can be obtained by solving the dynamic equation satisfied by the electron. And the influence of different electrostatic fields applied to the dielectric on the trajectory of electrons is analyzed. It is found that with the increase of the electrostatic field, the electrons quickly approach the dielectric plate, and finally move near the dielectric plate. Also, the total number of secondary electrons is decreasing accordingly. So, the multipactor discharge tends to go out. This conclusion can provide an idea for the suppression of the multipactor. Namely, applying a suitable electrostatic field on the dielectric surface can suppress multipactor involved in circulator junction.