Abstract: This paper uses the technique of particle-in-cell to build an accelerating section model with external circuit to simulate the electron effect of deuterium ion beam bombarding the target surface and analyze the influence of secondary electrons on acceleration voltage, quality of deuterium ion beam and energy beam bombarding the target dynamically. The results indicate that the acceleration voltage will decrease 45% when there is 0.06 A electron current, which then lead to the deterioration of deuterium ion beam's quality. The energy of beam bombarding the target decrease 43.5%, which will influence the neutron yield.