Since electrodes system is the key part of ArF excimer lasers, this paper is devoted to study the electrodes system of ArF excimer laser. By proper design of electrodes system, the optimized size of discharge zone is given and the approach of on-load voltage for cathode, anode and preionization electrodes is provided. Then a simplified configuration of electrodes system, consisting of cathode, anode, preionization electrodes, ceramic materials and working gases, is obtained. The electric field under different on-load voltages is calculated based on the simplified configuration of electrodes system. Simulation results show that electric field of discharge region is symmetrical, and the design of electrodes system is reasonable.