Abstract: To study the beam instability caused by wake field effect, a dielectric wall accelerator module model consisting of asymmetric pulse forming line, micro-stacked insulator and conductor layer was established, the finite integral method was used to simulate the wake field in the accelerating structure of dielectric wan accelerator (DWA) for high-current electron beam, wake potential and wake impedance were calculated for the single and two accelerating units. The results show the wake potential and wake impedance were small in x and y directions, the wake impedance can reach hundreds of ohms in z direction. It is proved that advantageous accelerating cavity length and path continuity, the influence of beam instability is relatively small, the DWA structure the beam transmission requirements