The present invention provides a method for monitoring ion implantation device performances. The method is characterized in that: a wafer to be measured is provided and put into a reaction cavity of an ion implantation device, and the method comprises the following steps of: providing an ion beam, wherein the ion beam comprises first ions and second ions; controlling a deflection radius of the ionbeam to separate the first ions from the second ions and implant the first ions into the wafer; and detecting whether the content of the second ions in the wafer exceeds a standard value or not, anddetermining that the ion device has performance faults when the detected content is larger than the standard value. The second ions are doped into the ion beam to control the deflection radius of theion beam to allow the first ions in the ion beam to be implant into the wafer and allow the second ions not to be implant into the wafer, if the content of the second ions in the wafer exceeds the standard value, it is shown that the ion device has performance faults, especially, there are problems in resolution analysis in a magnetic field of the ion device.