Abstract: Discharge cell fixed on metal objects surface has great application values, so it is necessary to study its discharge features. In this paper, the discharge process is simulated. To solve the float conductor boundary condition problem, a method is proposed by using charge conservation law and Gaussian law. It is found that the potential of float conductor is between the potential of anode and that of cathode and varies as the inner field of plasma region varies. Using PIC-MCC method, a simulation of the discharge process is successfully done. The results show that the existence of float conductor boundary changes the inner field structure, which is favorable for gas discharge as well as the formation of plasma region. Moreover, the float conductor forms a float electrode that drives away a