The present work aims to investigate the operation mechanism of one of the most important biological molecules, the potassium ion channel (KscA), using classical molecular dynamics simulations. Potassium ion channel is a membrane protein. An electric potential difference between channel ends creates an electric field along its axis, resulting in a flow of ions through the channel. Our simulations indicate that the ionic strength of the surrounding aqueous solution plays a critical role in the dynamics of potassium ions. In the simulation of the channel, an ionic strength can be applied by introducing a localized electric field. We find that applying an ionic strength close to the physiological conditions of an organism, weakens the main electric field and thus disturbs the flow of ions along the channel. By increasing the main electric field, this disruption is resolved and the flow of ions continues correctly. Moreover, we find that the simulation results are significantly influenced by the choice of truncation radii in the calculation of short- and long-range forces. We also investigate some possible events such as the trapping of an ion by carbonyl groups of selectivity filter, and ion cooling in the filter. It is concluded that, while classical simulations can successfully prove the possibility of an ion trapping, they can not prove the ion cooling in the filter. However, analyzing the self-correlation function of ion velocities shows a slowdown in ion motions in the filter.