Abstract: The beam nonuniformity is an important beam performance characteristic of the electron curtain accelerator. The major facts affecting beam nonuniformity are the electrode potential, the electrode shape and relative position of electrodes, which include cathode, reflector, grid and anode. In this paper, the nonuniformity of a homemade multi-filament curtain accelerator was discussed. The electron trajectories and beam nonuniformity for different structures of the electron guns were calculated. After analyzing and comparing these calculated results, some possible ways to improve the beam nonuiformity were proposed. The results will be useful as reference for redesigning new electron curtain accelerator.