A method capable of monitoring ion implantation. First, an ion beam and a workpiece are provided. Next, implant the workpiece by the ion beam and generate a profile having numerous signals relevant to respectively numerous relative positions between the ion beam and the workpiece, wherein the profile has at least a higher portion, a gradual portion and a lower portion. Therefore, by directly analyzing the profile without referring to a pre-determined profile and without using a profiler measuring the ion beam, some ion beam information may be acquired, such as beam height, beam width, ion beam current distribution on the ion beam cross-section, and so on, and the ion implantation may be monitored real-timely. Furthermore, when numerous workpieces are implanted in sequence, the profile(s) of one or more initially implanted workpiece(s) may be to generate a reference for calibrating the ion implantation of the following workpieces.