Molecular dynamic simulation was used to calculate the self-diffusion coefficients of ions in aqueous KCl solution. The simulations were performed for enough time (12 ns) in the form of all-atom to determine the accurate values of the self-diffusion coefficients. The values of the self-diffusion coefficients were calculated by Einstein equation. Two different force fields of Dang and Deublein were employed in the simulations, and we found that at low ion concentration (equal or less than 3mol/(kg of H2O)), the Dang force field is more accurate for prediction of the selfdiffusion coefficient of K+ ions and Deublein force field is more accurate for Cl- ions. An Arrhenius type equation was used to model the temperature dependence of the self-diffusion coefficients and the diffusion activation energies at different ion concentrations were reported.