The invention provided an ion implantation system. The ion implantation system comprises an ion emitting device and a target plate device; the target plate device comprises a graphite electrode unit and a power supply unit; the graphite electrode unit is mounted on the lower end of a support frame, and the graphite electrode unit is a hollow structure; the graphite electrode unit comprises a graphite electrode and a hollow region I, the graphite electrode is connected to the power supply unit; the area of the hollow region I is smaller than that of the wafer to be processed, and the sum of the area of the graphite electrode and the area of the hollow region I is larger than an implantation area of the ion beam. When the ion beam is implanted to the wafer to be processed on a target plate for ion implantation, the power supply unit applies a voltage to the graphite electrode to generate an electric field in the opposite direction from the electric field generated by the ion beam motion, accordingly, the speed of the ion beam implanted to a location outside the wafer to be processed is reduced, and secondary contamination during ion implantation is avoided, so as to perform an ion implantation process more efficiently.