The present invention provides a secondary electron device used for neutralizing a positive charge carried by an ion beam in an ion implantation process. The secondary electron device comprises a secondary electron emitter, a suspended baffle and a voltage source, wherein the electron emitter and the suspended baffle are arranged such that the ion beam passes through a space between the electron emitter and the suspended baffle to reach a wafer which accepts ion implantation, the suspended baffle and an ion beam system maintain insulated, and wherein a cathode of a voltage source is connected to the secondary electron emitter, and an anode of the voltage source is connected to the suspended baffle. By using the secondary electron device provided by the invention, a secondary electron fully passes through the ion beam, thus a better neutralizing effect is obtained in the ion implantation process, and an ion can be implanted into a wafer well.