Abstract: The azimuthator is an important part of plasma optical mass separation. The existing design for an azimuthator is based on the single particle orbit theory and focused on the movement of ions. In this paper, the particle simulation method is adopted to study the behavior of plasma crossing an azimuthator. The results show that electrons are bounded at the entrance of the azimuthator and an axial electric field is produced due to the charge separation. In order to better achieve the function of the azimuthator, a cathode is designed to transmit the electrons and to obtain a quasi-neutral plasma beam.