The characteristics of a real-time ion detectorplastic scintillator are experimentally investigated on an electrostatic accelerator. The sensitivity, the dynamic range, the energy response, and the spatial resolution of the plastic scintillator are calibrated, and then compared with those of other ion detectors. Meanwhile, the possibility for the plastic scintillator to be used as a diagnostic tool in laser-driven ion acceleration experiment is discussed. The plastic scintillator provides an efficient tool for online ion detection in the experiments of high-repetition-rate laser-driven ion accelerations.