This work aims to investigate the interaction of charged particles (Alpha and Proton) with polystyrene plastic scintillators by Monte Carlo simulation. The mass stopping power, projected range, and the ion distributions in the polystyrene plastic scintillator at an energy range of 0.01 MeV - 10,000 MeV, were computed by SRIM and FLUKA programs. The simulation results show that the mass stopping power of polystyrene plastic scintillators obtained by both programs are in good agreement. The projected range of alpha and protons particles penetrating in polystyrene increases with increasing energy. Finally, the 2D visualization of ion distributions and ion ranges for alpha and proton particles were reported.