This invention discloses an ion implantation apparatus that has an ion source and an ion extraction device for extracting an ion beam therefrom. The ion implantation apparatus includes an ion beam sweeping-and-deflecting device disposed immediately next to the ion extraction device. The ion implantation apparatus further includes a magnetic analyzer for guiding the ion beam passed through the deflecting-and-sweeping device. The mass analyzer is also used for selecting ions with specific mass-to-charge ratio to pass through a mass slit to project onto a substrate. The sweeping-and-deflecting device is applied to deflect the ion beam to project through the magnetic mass analyzer and the mass slit for sweeping the ion beam over a surface of the substrate to carry out an ion implantation.